The present invention discloses an overcurrent protection circuit for a light source driving module and a related backlight module. The overcurrent protection circuit includes an average value overcurrent protection circuit for detecting an average voltage at a node where the switch is connected to the detection resistor and generating the turning-off signal to turn off the switch when the average voltage is larger or equal to a threshold average voltage, wherein the average voltage is formed by an average current of the switch. Through the above-mentioned mechanism, the present invention can prevent the working power of a power device from being larger than its rated power. Therefore, it also prevents the power device from catching a fire due to a potential high temperature.