You can go to the actual precicnt data and just use the sum function in the excel file as ohio does have matching precincts to township lines.
I got the precinct data but sadly I am have sure which city or town it belongs, since the excel file doesn't give clear information about which city it belongs. Plus seems that the shapefile of OH county subdivision doesn't give some village text file of OH, For instance the village of West Union, Ohio doesn't appear in the shapefile, I wonder How can I do this without a file which present all the town and city...
Too bad
In Ohio, at least historically, a village is not independent of its township. To confuse matters, village names are often the same as that of the township.
This is a map of Adams County, Ohio.
The heaviest lines are county subdivisions (in Adams County, these are all townships). In more populous areas many/most will be cities.
The finer lines, along with the names are VTD (voting districts or election precincts). The names are of the VTD, though some VTD's are coterminous with the township of the same name. But Locust Grove VTD is coterminous with Franklin Township.
Tiffin Township includes the VTD's of Tiffin East, Tiffin West, West Union A, and West Union B. The latter two are also within the village of West Union. Villages are not necessarily contained within a single township, and VTD's don't necessarily match villages.
VTD's don't 100% line up with townships. For example Seaman Village VTD has a tiny bit in Wayne Township (Wayne Township VTD is not the entirety of Wayne Township). Part of the village of Seaman is not in Seaman Village VTD.
The green areas are places. In Census terms a place includes both incorporated cities and villages (formal governments) and CDP (census designated places), which are just areas of settlement, which the census bureau in conjunction with local authorities has delineated for statistical purposes.
Not every village has a voting district. In Adams County, the green blobs in Wayne and Sprigg Township are CDPS. The little green blob in Green Township is the Village or Rome (incidentally, even locals don't call the village by its proper name of Rome. Instead they call it Stout after the founder in 1835, and also used by the USPS.
I know where there is a file with VTD-Census Block associations. I don't know where there is a file with County Subdivision-Census Block associations. I'm sure it can be done in QGIS.
With the two, you could determine the area of each VTD that is in each County Subdivision (in almost all cases this will be the entire area of the VTD). For the others, you can assign a VTD to a County Subdivision based on the majority of the area.
