Crystal Township is one of sixteen townships in Hancock County, Iowa, USA. As of the 2000 census, its population was 529.
Crystal Township was founded in 1869. The township was named from Crystal Lake.
According to the United States Census Bureau, Crystal Township covers an area of 35.5 square miles (91.96 square kilometers); of this, 35.11 square miles (90.93 square kilometers, 98.88 percent) is land and 0.4 square miles (1.03 square kilometers, 1.12 percent) is water.
The township contains Crystal Township Cemetery.