Sims Township is a general law township of Arenac County in the U.S. state of Michigan. The population was 1,091 at the 2000 census.

According to the United States Census Bureau, the township has a total area of 43.7 square miles (113.2 km²), of which, 11.5 square miles (29.9 km²) of it is land and 32.2 square miles (83.3 km²) of it (73.61%) is water.