In stimulated scattering energy signal detection of inertial confinement fusion (ICF), background noise has a serious impact on the extraction of useful information. Aiming at this issue, a new variable parameters amplification and filtering circuit (VPAFC) is designed, and a denoising method based on denoising source separation (DSS) is proposed. By using variable gain amplifier, bandwidth-adjustable filter and signal noise reduction software, the whole system can not only adapt to the amplitude change of signal in weak signal detection, but also restrain the noise both outside useful signal band and structural interference inside. In order to test the new circuit and the efficiency of the algorithm, a system with weak scattering light energy signal detection device and data acquisition is constructed. Experimental result shows that the system can fit the amplitude change quickly by adjusting parameters online, and its output can keep a signal-to-noise ratio above 40 dB when the input voltage drops to 2 μV.