A polarity correction circuit for dimmer includes a control circuit, an adjustment circuit, and a detection circuit. The adjustment circuit is connected to the control circuit, a working voltage input end, and a dimmer, and the adjustment circuit includes several switches. The adjustment circuit receives a dimming signal of the dimmer. The detection circuit is connected to the dimmer and the control circuit, the detection circuit detects the dimming signal to generate a reference voltage, and the detection circuit transmits the reference voltage to the control circuit. The control circuit maintains the switch states of the switches of the adjustment circuit unchanged or adjust the switch states of the switches of the adjustment circuit according to the reference voltage.