The present disclosure relates to a grass trimmer (100) comprising a main body (1) and a trimming device (2). The main body (1) comprises an operating device (10) and a power source. The trimming device (2) comprises: a grass cutting assembly having a cutting member(23) and a power head for rotating the cutting member (23). The power head comprises: a housing (21), a rotor assembly and a stator assembly. The housing (21) is formed integrally and defining an accommodation chamber (211). The rotor assembly is received in the accommodation chamber (211) of the housing (21) and comprises a rotor sleeve which is rotary around a pivotal axis. The stator assembly is at least partly received in the rotor sleeve. The rotor assembly further comprises two or more magnetic pieces at an inner wall of the rotor sleeve. The stator assembly comprises a stator support and a coil assembly. The stator support comprises: a mounting portion and a supporting portion. The coil assembly is disposed in the rotor sleeve by the supporting portion. The grass trimmer (100) has a small size, is lightly-weighted, and has a low manufacturer cost.
