Abstract: Considering the influence on load capacity and transient response caused by the traditional linear slope compensation The proportional to the frequency of the charge and discharge current is used to form the first order slope current, then use it together with the input and output of the bipolar transistor characteristics realize quadratic slope compensation circuit which can work in different frequency and slope peak current changed with the duty cycle was proposed. The lack of the slope compensation effectively reduced. its performances have been verified by Hspice simulation using the 0.5 um BCD process.