A vacuum cleaner and suction nozzle thereof. The vacuum cleaner has a housing, dust collecting unit, filter assembly, motor assembly and roller brush. The suction nozzle has a bottom housing, front cover and roller brush. The housing includes a concave cavity; the bottom housing and the front cover latch together to form a chamber; the roller brush assembly and the separation piece fit into this chamber; the separation piece corresponds to a transmission component of the roller brush. When rotating at high speed, the roller brush forms a seamless and closed separation face with the separation piece, preventing foreign matter from entering the transmission component, thus avoiding reduced suction and damage due to a tangled synchronous belt or a shaft jamming a roller brush bearing.