import win32com
from win32com.client import Dispatch, constants

ppt = win32com.client.Dispatch('PowerPoint.Application')
pptSel = ppt.Presentations.Open('c:/1.ppt',ReadOnly=1, Untitled=0, WithWindow=0)
win32com.client.gencache.EnsureDispatch('PowerPoint.Application')
slide_count = pptSel.Slides.Count
ppt.Quit()
print(slide_count)
#//python/8338