The invention discloses an electronic atomizing device and an atomizer thereof. The atomizer includes a main body unit and a suction nozzle unit. The main body unit includes a liquid storage cavity, an atomization assembly fluidly connected to the liquid storage cavity and a first pipe fluidly connected to the atomization assembly. The liquid storage cavity includes a liquid injection port. The suction nozzle unit is detachably disposed on an upper end of the first pipe and seals the liquid injection port. The suction nozzle unit includes a second pipe, an operating member and an elastic member. The second pipe is detachably screwed to the first pipe and fluidly connected to the first pipe. The operating member is sleeved on the second pipe and axially movable relative to the second pipe between a first position and a second position, and rotatable around an axis of the second pipe.