The invention relates to a mobile seat used for a children car. The mobile seat used for the children car comprises a base, a base plate, a seat moving lock and a seat body, wherein the base plate, the seat moving lock and the seat body are sequentially distributed on the base. The base plate is fixedly arranged on the base, the seat moving lock is fixed to the bottom of the seat body, and a containing groove used for containing the seat moving lock is concavely formed in the front end of the base plate. The seat moving lock is slidably connected into the containing groove. Compared with the prior art, the mobile seat used for the children car is simple in structure and convenient to use, the seat body can move front and back on the base through the seat moving lock, and riding requirements for children of different ages and heights can be met; meanwhile, through clamped-connection cooperation of two T-shaped pin grooves and T-shaped pins, the sliding fit between the seat body and the base is more reliable, and the seat body is not prone to shaking; and in addition, the mobile seat used for the children car can be adjusted front and back with one single hand through a pull rope, operation is convenient, use safety of children is guaranteed, and the use enjoyment of the children electric car is also improved.