The Great Valley Grasslands State Park is a state park and natural area in Gustine, California. It is a part of the Grasslands Ecological Area that is jointly managed to preserve wildlife values.

The Great Valley Grasslands State Park is best noted for being one of the last few examples of native grasslands that carpets the floor of the Central Valley. It is also a part of the largest remaining flanking chunk of wetlands in the state. It is home to numerous rare and endangered animal and plant life like the alkali sacaton and the Delta button celery.

Aside from exploring the site for nature study, it is also popular for hiking, biking, and fishing. Visitors also usually come around the springtime to see the wildflowers bloom.