调用方法：public string ConvertToChineseNumber(string old){Chinese ch = new Chinese();long num = Convert.ToInt64(old);string re = ch.returnResult(num);if (re.StartsWith("壹拾")){re = re.Substring(1, re.Length - 1);}return (re);}

完整代码
using System;
using System.Collections.Generic;
using System.Text;namespace Public
{class Chinese{public string returnResult(long num){string numStr = num.ToString();if (numStr.Length > 8 & numStr.Length < 16){string[] firstSplit = new string[2];firstSplit[0] = numStr.Substring(0, numStr.Length - 8);firstSplit[1] = numStr.Substring(numStr.Length - 8, 8);string result1 = getString(firstSplit[0]) + "億";string result2 = getString(firstSplit[1]);return result1 + result2;}else{return getString(numStr);}}public string getString(string str){if (str.Length > 4){string[] secondSplit = new string[2];secondSplit[0] = str.Substring(0, str.Length - 4);secondSplit[1] = str.Substring(str.Length - 4, 4);string result1 = getRe(secondSplit[0]);string result2 = getRe(secondSplit[1]);if (!secondSplit[0].Equals("0000")){result1 += "萬";}return result1 + result2;}else{return getRe(str);}}int[] value = { 1000, 100, 10 };public string getRe(string doWith){char[] number = doWith.ToCharArray();int length = number.Length;string re = "";for (int i = 0; i < length; i++){switch (number[i]){case '0':if (re.EndsWith("零")){re += "";}else{re += "零";}break;case '1':re += "壹";break;case '2':re += "贰";break;case '3':re += "叁";break;case '4':re += "肆";break;case '5':re += "伍";break;case '6':re += "陆";break;case '7':re += "柒";break;case '8':re += "捌";break;case '9':re += "玖";break;}int index = (int)Math.Pow(10, length - i - 1);if (number[i].ToString() == "0"){index = -1;}switch (index){case 1000:re += "仟";break;case 100:re += "佰";break;case 10:re += "拾";break;}}if (re.EndsWith("零")){re = re.Substring(0, re.Length - 1);}return re;}}
}