The invention provides an atomizer and an electronic cigarette thereof. The atomizer comprises a switching device, a liquid storage assembly and an atomization assembly, wherein the atomization assembly is arranged in the liquid storage assembly, the switching device comprises a moving piece and a stationary piece which are arranged in a matched mode, the moving piece can move with respect to the stationary piece to switch the atomizer between a liquid injection rate and an inflow air regulation state, and a liquid injection port and an air inlet which are correspondingly communicated respectively in the liquid injection rate and the inflow air regulation state are formed in the moving piece and the stationary piece. In addition, when the atomizer is in the liquid injection rate, the air inlet is closed, and the situation that pressure difference is produced when inflow air is led, and a cigarette smoke solution likely seeps from an atomization head during liquid injection is avoided.