The invention discloses a baby safety seat. The baby safety seat comprises a seat bracket and a chassis, wherein the seat bracket is rotatablely arranged on the upper surface of the chassis; the seat bracket at least comprises a seat plate; a baffle plate and a back plate are respectively hinged to the two opposite sides of the seat plate; and a plurality of locking devices are fixed to the lower surface of the chassis. Through the adoption of the baby safety seat disclosed by the invention, the problem that an ordinary safety seat is only suitable for a baby to ride and does not have a function of allowing the baby to lie flat, and when the baby needs to have a sleep on a car, the ordinary safety seat cannot meet the need is solved.