A cutter assembly of lawnmower includes a base body, a fixing plate, a motor, a cutter, and a restriction assembly. The base body defines an axial direction. The fixing plate is disposed on the base body and has a first circumferential wall. A first bearing is received inside the first circumferential wall. The motor is disposed on the base body and includes a base seat, a rotor, and a rotation axle. The base seat is disposed on the base body and has a second circumferential wall. Two second bearings are received inside the second circumferential wall. The rotation axle and the rotor are linked-up and inserted through the first bearing and the second bearings.
