string strCon = "Provider=microsoft.jet.oledb.4.0;data source=" + filePath + ";extended properties=excel 8.0";
OleDbConnection conn = new OleDbConnection(strCon);
string strSql = "select * from [Sheet1$]";
OleDbCommand cmd = new OleDbCommand(strSql, conn);
OleDbDataAdapter da = new OleDbDataAdapter(cmd);
da.Fill(ds, "Sheet1");