I'd suggest to use
EPPlus[
^].
FileInfo fi = new FileInfo("FullFileNameHere");
using(ExcelPackage xlPackage = new ExcelPackage(fileInfo))
{
List<string> sheets = xlPackage.Workbook.Worksheets.Select(x=>x.Name).ToList();
foreach (string s in sheets)
cmbKit.Items.Add(s);
}
As you can see, the code is very short. It executes very fast.
More about EPPlus software you'll find here:
EPPlus 5[
^]