In order to overcome the problems of limited boost capacity and high switching stress of the quadratic boost converter, a non-isolated improved quadratic boost high-gain DC-DC converter is proposed, with two topological structures. The operation principles of the two topologies are analyzed, and the voltage gain and switching stress of the circuit topology are theoretically deduced and compared with existing converters. The proposed converter raises the output gain while reducing the switching stress and enhancing the efficiency. A simulation model is established in MATLAB/Simulink, and the simulation results verify the correctness of the theoretical calculations. Finally, an experimental prototype of the converter is built, and the feasibility of the converter design scheme is verified through the comparative analysis of theoretical deduction and experimental results.