Noise can be used by the nonlinear stochastic resonance system to enhance the ability of weak signal detection, which creates a new method of weak signal detection under heavy background noise. A hardware circuit system, designed based on the basic principle of stochastic resonance, is used to detect single-frequency and multi-frequency weak signals. When the signal with noise that simulates actual engineering situation is introduced into the system, the spectrum of samples of the output signal shows that single-frequency and multi-frequency weak signals under heavy background noise can be detected by the technology based on stochastic resonance effectively. The application field of weak signal detection technology based on stochastic resonance is entended by the effective detection of mutil-frequency weak signal, and the degradation of signal recognition by low-frequency noise is eliminated by digital filtering effectively. The weak signal detection technology based on stochastic resonance has potential applications in the information recognition and information processing.