using System.Data.OleDb;

添加一个button控件，一个textBox控件，用于显示选择路径 

private void loadxls()
{

        String  fileName = textBox1.Text;  
        String connectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:/Members.xls;Extended Properties='Excel 8.0;HDR=YES;IMEX=1';";

        string strSQL = "SELECT \* FROM \[Sheet1$\]";

        OleDbConnection excelConnection = new OleDbConnection(connectionString);  
        excelConnection.Open();        // This code will open excel file.

        OleDbCommand dbCommand = new OleDbCommand(strSQL, excelConnection);  
        OleDbDataAdapter dataAdapter = new OleDbDataAdapter(dbCommand);

        // create data table  
        DataTable dTable = new DataTable();  
        dataAdapter.Fill(dTable);  
        dataGridView1.DataSource = dTable;

        dTable.Dispose();  
        dataAdapter.Dispose();  
        dbCommand.Dispose();

        excelConnection.Close();  
        excelConnection.Dispose();  
    }

    private void button1\_Click(object sender, EventArgs e)  
    {  
        OpenFileDialog openFileDialog1 = new OpenFileDialog();  
        openFileDialog1.Filter = "Excel文件(\*.xls)|\*.xls";

        if (openFileDialog1.ShowDialog() == DialogResult.OK)  
        {  
            textBox1.Text = openFileDialog1.FileName;  
            loadxls();  
        }  
    }