function HexToStr(str: string): string;
  function HexToInt(hex: string): integer;
  var
    i: integer;
    function Ncf(num, f: integer): integer;
    var
      i: integer;
    begin
      Result := 1;
      if f = 0 then exit;
      for i := 1 to f do
        result := result * num;
    end;
    function HexCharToInt(HexToken: char): integer;
    begin
      if HexToken > #97 then
        HexToken := Chr(Ord(HexToken) - 32);
      Result := 0;
      if (HexToken > #47) and (HexToken < #58) then { chars 0....9 }
        Result := Ord(HexToken) - 48
      else if (HexToken > #64) and (HexToken < #71) then { chars A....F }
        Result := Ord(HexToken) - 65 + 10;
    end;
  begin
    result := 0;
    hex := ansiuppercase(trim(hex));
    if hex = '' then
      exit;
    for i := 1 to length(hex) do
      result := result + HexCharToInt(hex[i]) * ncf(16, length(hex) - i);
  end;
var
  s, t: string;
  i, j: integer;
  p: pchar;
begin
  s := '';
  i := 1;
  while i < length(str) do begin
    t := str[i] + str[i + 1];
    s := s + chr(hextoint(t));
    i := i + 2;
  end;
  result := s;
end;

 ///<summary>
    /// 从16进制转换成汉字
    /// </summary>
    /// <param name="hex"></param>
    /// <param name="charset">编码,如"utf-8","gb2312"</param>
    /// <returns></returns>
    public  string HexToStr(string hex, string charset)
    {
        if (hex == null)
            throw new ArgumentNullException("hex");
        hex = hex.Replace(",", "");
        hex = hex.Replace("\n", "");
        hex = hex.Replace("\\", "");
        hex = hex.Replace(" ", "");
        if (hex.Length % 2 != 0)
        {
            hex += "20";//空格
        }
        // 需要将 hex 转换成 byte 数组。 
        byte[] bytes = new byte[hex.Length / 2];

        for (int i = 0; i < bytes.Length; i++)
        {
            try
            {
                // 每两个字符是一个 byte。 
                bytes[i] = byte.Parse(hex.Substring(i * 2, 2),
                System.Globalization.NumberStyles.HexNumber);
            }
            catch
            {
                // Rethrow an exception with custom message. 
                throw new ArgumentException("hex is not a valid hex number!", "hex");
            }
        }
        System.Text.Encoding chs = System.Text.Encoding.GetEncoding(charset);
        return chs.GetString(bytes);
    }