1，首先导入命名空间：using System.Runtime.InteropServices;

2，声明API函数

        [DllImport("kernel32")]
        private static extern long WritePrivateProfileString(string section, string key, string val, string filePath);

3,创建ini文件

            WritePrivateProfileString("MyQQ", "ID", "798033502", @"C:\QQ.ini");
            WritePrivateProfileString("MyQQ", "PWD", "**********", @"C:\QQ.ini");
4，声明API函数

        [DllImport("kernel32")]
        private static extern int GetPrivateProfileString(string section, string key, string def, StringBuilder retVal, int size, string filePath);

5，读取ini文件

           StringBuilder temp = new StringBuilder();
            GetPrivateProfileString("MyQQ", "ID", "账号错误", temp, 255, @"C:\QQ.ini");
            string ID = temp.ToString();
            GetPrivateProfileString("MyQQ", "PWD", "读取出错", temp, 255, @"C:\QQ.ini");
            string PWD = temp.ToString();
            MessageBox.Show(ID + ":" + PWD);

6完整代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace WindowsFormsApplication1
{
    public partial class Main : Form
    {
        public Main()
        {
            InitializeComponent();
        }
        [DllImport("kernel32")]
        private static extern long WritePrivateProfileString(string section, string key, string val, string filePath);
        private void button1_Click(object sender, EventArgs e)
        {
            WritePrivateProfileString("MyQQ", "ID", "798033502", @"C:\QQ.ini");