using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Spreadsheet;
using System.Data;
...

private DataTable ReadExcelSheetToDataTable(string pathExcelFile)
{
	DataTable dt = new DataTable();
	
	dt.Columns.Add("Column 1");
	dt.Columns.Add("Column 2");
	dt.Columns.Add("Column 3");
	dt.Columns.Add("Column 4");
	dt.Rows.Add();  // First of all add an Empty Row

	using (SpreadsheetDocument doc = SpreadsheetDocument.Open(pathExcelFile, false))
	{
		// Read the first Sheet
		Sheet sheet = doc.WorkbookPart.Workbook.Sheets.GetFirstChild<Sheet>();
		Worksheet worksheet = (doc.WorkbookPart.GetPartById(sheet.Id.Value) as WorksheetPart).Worksheet;
		IEnumerable<Row> rows = worksheet.GetFirstChild<SheetData>().Descendants<Row>();
		
		int counter = 0;
		foreach (Row row in rows)
		{
			counter = counter + 1;

			// Skip first 3 rows as header
			if (counter ≥ 3)
			{                        
				dt.Rows.Add();
				int i = 0;
				foreach (Cell cell in row.Descendants<Cell>())
				{
					dt.Rows[dt.Rows.Count - 1][i] = GetCellValue(doc, cell);
					i++;
				}
			}
		}

	}

	return dt;
}

private string GetCellValue(SpreadsheetDocument doc, Cell cell)
{
	string cellValueText = cell.CellValue.InnerText;
	Double value = Double.Parse(cellValueText, NumberStyles.AllowExponent | NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture) / 100;

	if (cell.DataType != null && cell.DataType.Value == CellValues.SharedString)
	{
		return doc.WorkbookPart.SharedStringTablePart.SharedStringTable.ChildElements.GetItem(int.Parse(cellValueText)).InnerText;
	}
	return value.ToString();
}