LED brightness adjusting circuit

The embodiment of the invention discloses an LED brightness adjusting circuit. The circuit comprises a brightness adjusting module and a parameter adjusting module. Wherein the brightness adjusting module comprises a light emitting diode to be controlled and a transistor connected with the light emitting diode in series, and the brightness adjusting module is used for adjusting the brightness of the light emitting diode according to input parameters of the transistor; the parameter adjusting module is used for being connected with an IO port of a main control chip through at least one signal input end and adjusting the input parameters according to the output state of the IO port. According to the technical scheme, a special IO port used for achieving special functions does not need to be arranged on the main control chip, namely, a special chip does not need to be used, and on the basis of providing various brightness level control, the implementation cost is effectively reduced, so that the user experience