1. 从byte[]转换成string

string result = System.Text.Encoding.UTF8.GetString(byteArray);

2.从string 转换成byte[]

System.Text.ASCIIEncoding  encoding=new System.Text.ASCIIEncoding();

    Byte[] bytes = Encoding.GetBytes(yourString);

参考网址：

https://social.msdn.microsoft.com/Forums/vstudio/en-US/08e4553e-690e-458a-87a4-9762d8d405a6/how-to-convert-the-string-to-byte-in-c-?forum=csharpgeneral