check this code
using excel = Microsoft.Office.Interop.Excel;
excel.Application eApp = new excel.Application();
excel.Worksheet eWs = new excel.Worksheet();
excel.Workbook eWs1;
eWs1 = (excel.Workbook)(eApp.Workbooks.Add([Excel Path]));
eWs = (excel.Worksheet)eWs1.Worksheets[0];
eApp.Visible = true;
DataTable dt = new DataTable();
eWs.Select(Type.Missing);
int iRow = 1;
if (dt.Rows.Count > 0)
{
foreach (DataRow dr in dt.Rows)
{
eWs.Cells[iRow, 1] = Convert.ToString(dr["column1"]);
eWs.Cells[iRow, 2] = Convert.ToString(dr["column2"]);
eWs.Cells[iRow, 3] = Convert.ToString(dr["column3"]);
eWs.Cells[iRow, 4] = Convert.ToString(dr["column4"]);
iRow++;
}
}
eWs1.SaveAs([Excel Path], Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);