Abstract: Based on FVF structure, a new dynamic slope compensation circuit is designed to detect the input and output voltage, generate dynamic compensation voltage, and improve the response speed of the loop as much as possible on the basis of stable loop.The equivalent small signal model is established for each module of the control circuit of the switching power supply, and the open-loop gain function of the internal current loop and external voltage loop is analyzed to obtain the cause of sub-ramp oscillation of the system.The stability and response speed of voltage and current loop under dynamic slope compensation scheme and constant slope compensation scheme were compared, and matlab software was used for simulation verification.The simulation results show that the dynamic slope compensation circuit can effectively suppress the sub-slope oscillation and improve the dynamic response speed of the system.