The invention provides an infant car seat and an elastic crotch belt thereof. The crotch belt assembly is used for the infant car seat and the infant car seat comprises a safety belt, wherein the safety belt comprises a shoulder belt and the crotch belt assembly; a buckling tool is arranged on the shoulder belt; the crotch belt assembly comprises a crotch belt set with a buckling tool body, a crotch belt protection sheet for covering the crotch belt body, and an elastic body; the buckling tool body is connected to one end of the crotch belt assembly, and the other end of the crotch belt assembly is connected to the infant car seat; the buckling tool body is used for connecting the buckling tool to combine the shoulder belt; the crotch belt protection sheet has a containing space; the elastic body is arranged in the containing space, and at least a part of the elastic body is arranged in the infant car seat; the crotch belt assembly is maintained in the required position in a nonuse state by utilizing the elastic body; users can not regulate and remove the crotch belt; and the elastic body can be exchanged and shielded by the crotch belt protection sheet to avoid the elastic body from being contaminated and damaged and dropping.