The invention provides a partial discharge signal detecting method based on a coupled Duffing oscillator, comprising the following steps: obtaining a to-be-detected digital signal after passing a to-be-detected signal through an A/D converter; inputting the to-be-detected digital signal into a coupled Duffing oscillator system; using the fixed-step-size fourth-order Runge-Kutta method to solve thedifference of the state variable between oscillators; and regarding the difference of the state variable between oscillators as a partial discharge signal in the to-be-detected signal. The method ofthe invention adopts the Duffing oscillator system composed of three oscillators, achieves the strong noise suppression capability and can effectively detect the partial discharge signal; the coupledoscillator is solved by initial value recursion, the operation speed is better than that of the existing method, and the method is suitable for real-time operation and has an advantage in the on-linedetection system of the discharge signal; and the narrow signal detection capability is superior to that of the existing detection method.