private void button1_Click(object sender, EventArgs e)
        {
            string textfile = @"C:/textfile1.txt";
            string file = new FileInfo(@"C:/textfile1.txt").DirectoryName;
            string constr = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + file + ";Extended Properties=\"text;\";";
            OleDbConnection con = new OleDbConnection(constr);
            textfile = (new FileInfo(textfile)).Name;
            string comstr = "SELECT  * FROM  " + textfile;
            OleDbCommand com = new OleDbCommand(comstr);
            com.Connection = con;
            OleDbDataAdapter da = new OleDbDataAdapter(com);
            DataSet ds = new DataSet();
            da.Fill(ds);
            dataGridView1.DataSource = ds.Tables[0];
       }

แล้วให้ เรียกใช้

using System.IO;
using System.Data.OleDb;