São Lourenço do Sul is a Brazilian municipality in the state of Rio Grande do Sul.

The municipality had 43,111 inhabitants in the last Census (2010).

It is located at the west bank of the big lagoon Lagoa dos Patos.

The municipality contains part of the 7,993-hectare (19,750-acre) Camaquã State Park, created in 1975.

This geographical article relating to Rio Grande do Sul is a stub.