#region 阴历转阳历

        /// <summary>
        /// 获取指定年份春节当日（正月初一）的阳历日期
        /// </summary>
        /// <param name="year">指定的年份</param>
        private  DateTime GetLunarNewYearDate(int year)
        {
            DateTime dt = new DateTime(year, 1, 1);
            int cnYear = calendar.GetYear(dt);
            int cnMonth = calendar.GetMonth(dt);

            int num1 = 0;
            int num2 = calendar.IsLeapYear(cnYear) ? 13 : 12;

            while (num2 >= cnMonth)
            {
                num1 += calendar.GetDaysInMonth(cnYear, num2--);
            }

            num1 = num1 - calendar.GetDayOfMonth(dt) + 1;
            return dt.AddDays(num1);
        }

        /// <summary>
        /// 阴历转阳历
        /// </summary>
        /// <param name="year">阴历年</param>
        /// <param name="month">阴历月</param>
        /// <param name="day">阴历日</param>
        /// <param name="IsLeapMonth">是否闰月</param>
        public  DateTime GetDateFromLunarDate(int year, int month, int day, bool IsLeapMonth)
        {
            if (year < 1902 || year > 2100)
                throw new Exception("只支持1902～2100期间的农历年");
            if (month < 1 || month > 12)
                throw new Exception("表示月份的数字必须在1～12之间");

            if (day < 1 || day > calendar.GetDaysInMonth(year, month))
                throw new Exception("农历日期输入有误");

            int num1 = 0, num2 = 0;
            int leapMonth = calendar.GetLeapMonth(year);

            if (((leapMonth == month + 1) && IsLeapMonth) || (leapMonth > 0 && leapMonth <= month))
                num2 = month;
            else
                num2 = month - 1;

            while (num2 > 0)
            {
                num1 += calendar.GetDaysInMonth(year, num2--);
            }

            DateTime dt = GetLunarNewYearDate(year);
            return dt.AddDays(num1 + day - 1);
        }

        /// <summary>
        /// 阴历转阳历
        /// </summary>
        /// <param name="date">阴历日期</param>
        /// <param name="IsLeapMonth">是否闰月</param>
        public  DateTime GetDateFromLunarDate(DateTime date, bool IsLeapMonth)
        {
            return GetDateFromLunarDate(date.Year, date.Month, date.Day, IsLeapMonth);
        }

        #endregion

        #region 阳历转阴历
        public string SolarToChineseLunisolarDate(DateTime solarDateTime)
        {
            System.Globalization.ChineseLunisolarCalendar cal = new System.Globalization.ChineseLunisolarCalendar();

            int year = cal.GetYear(solarDateTime);
            int month = cal.GetMonth(solarDateTime);
            int day = cal.GetDayOfMonth(solarDateTime);
            int leapMonth = cal.GetLeapMonth(year);
            return string.Format("农历{0}{1}（{2}）年{3}{4}月{5}{6}"
                                , "甲乙丙丁戊己庚辛壬癸"[(year - 4) % 10]
                                , "子丑寅卯辰巳午未申酉戌亥"[(year - 4) % 12]
                                , "鼠牛虎兔龙蛇马羊猴鸡狗猪"[(year - 4) % 12]
                                , month == leapMonth ? "闰" : ""
                                , "无正二三四五六七八九十冬腊"[leapMonth > 0 && leapMonth <= month ? month - 1 : month]
                                , "初十廿三"[day / 10]
                                , "日一二三四五六七八九"[day % 10]
                                );
        }
        #endregion

 阳历转阴历

  #region 阳历转阴历
        public string SolarToChineseLunisolarDate(DateTime solarDateTime)
        {
            System.Globalization.ChineseLunisolarCalendar cal = new System.Globalization.ChineseLunisolarCalendar();

            int year = cal.GetYear(solarDateTime);
            int month = cal.GetMonth(solarDateTime);
            int day = cal.GetDayOfMonth(solarDateTime);
            int leapMonth = cal.GetLeapMonth(year);
            return string.Format("农历{0}{1}（{2}）年{3}{4}月{5}{6}"
                                , "甲乙丙丁戊己庚辛壬癸"[(year - 4) % 10]
                                , "子丑寅卯辰巳午未申酉戌亥"[(year - 4) % 12]
                                , "鼠牛虎兔龙蛇马羊猴鸡狗猪"[(year - 4) % 12]
                                , month == leapMonth ? "闰" : ""
                                , "无正二三四五六七八九十冬腊"[leapMonth > 0 && leapMonth <= month ? month - 1 : month]
                                , "初十廿三"[day / 10]
                                , "日一二三四五六七八九"[day % 10]
                                );
        }
  #endregion

调用方法：

    //阴历转阳历
    public void GetDayFromLunarDate(DateTime time)
    {
        ChineseCalendar cc = new ChineseCalendar(time);
        cc.GetDateFromLunarDate(time, true);
    }
    //阳历转阴历
    public void GetLunarDateFromDay(DateTime time)
    {
        ChineseCalendar cc = new ChineseCalendar(time);
        string LunarDate = cc.SolarToChineseLunisolarDate(time);
    }