A child safety seat includes a seat body, and a restraining harness coupled to the seat body. The seat body has a front surface and a rear surface opposite to each other, the front surface being adapted to provide support for a child placed in the seat body. The restraining harness includes a restraining belt and an adjusting buckle coupled to each other, the restraining belt having a front belt portion extending in front of the front surface and a rear belt portion extending behind the front surface, the adjusting buckle being provided on the rear belt portion and being operable to adjust a length of the front belt portion.