The invention discloses an interleaved parallel LED drive circuit based on a quadratic Buck and its working method, belonging to the field of power electronics, including an AC input, a rectifier bridge D1, a filter inductor Lf, a filter capacitor Cf, and two switch tubes Q1 and Q2 , diodes D2, D3, D4, D5, D6, inductors L1, L2, L3 and energy storage capacitors C1, C2, output capacitor Co and LED load. Based on the existing secondary buck converter circuit topology, a switch network composed of switch tube Q2, inductor L3, capacitor C2 and diode D6 is added to form an interleaved parallel structure, which effectively reduces the output current ripple and reduces The filter inductor design reduces the volume of the converter, improves system stability and power density, and realizes high efficiency and high power factor operation.