A car humidifier, which includes a base, a water tank connecting to the base, a waterproof washer for the water tank, an absorbent sponge stick extended between the base and the water tank, an atomization film supported by a bottom support in the base having direct contact between the absorbent sponge stick and the water tank, a waterproof ring for the bottom support, a circuit board electrically connected to the atomization film, an upper case having a spray opening communicate with the atomization film and connected to the base, a positioning seat for rotation mounted to two sides of the base, a cigarette lighter plug connected to the circuit board, a positioning plug coupling to the positioning seat extended on top of the cigarette lighter plug, thereby unnecessary wiring is eliminated. This design is simple, elegant, convenience and easy for use.