Sub test()
Dim lastRow As Long, myRow As Long, mySheet As Worksheet
lastRow = ThisWorkbook.Sheets("Sheet1").Cells(Rows.Count, 1).End(xlUp).Row
For myRow = 2 To lastRow Step 900
Set mySheet = Worksheets.Add
Sheets("Sheet1").Rows(myRow & ":" & myRow + 899).EntireRow.Copy mySheet.Range("A1")
Next myRow
End Sub