A novel two winding coupled-inductor step-up gain boost-flyback converter is proposed in this paper. The proposed converter consists of a boost cell and a flyback cell, with a two winding coupled-inductor to achieve high step-up voltage gain at reasonable duty ratio. The voltage gain of the proposed converter is improved with input-parallel output-series of two windings of coupled-inductor. The operating principle and steady state characteristic of the proposed converter is analyzed. Finally, a 110W, 25V input, 200V output prototype has been built to verify the theoretical analysis results.