A PWM circuit is disclosed in the application, which includes: a PWM counter, a reference value setting register, a frequency multiplier and a comparator, where the frequency multiplier is adapted to increase the frequency of a clock signal input and to output the clock signal with the increased frequency to the PWM counter. An LED drive circuit is further disclosed in the application. The frequency of a PWM input clock signal is increased to N times of the original frequency of the PWM input clock signal by the frequency multiplier, so that the counting cycle of the PWM counter is shortened to 1/N of the original counting cycle of the PWM counter. Therefore, in the dynamic LED display screen, the refresh frequency can be increased to N times of the original refresh frequency while the original resolution is maintained.