The paper presents a special function improved Fly back converter is operate with better efficiency and compact size,which is prevail over most of the basic fly back converter downside s,and also keeping its inexpensiveness and lucidity . In certain,the converter permits the MOSFET OFF voltage to be less in amount and clamped to the input,thus healing the transformer leakage energy. As a result of effect,the duty cycle can be increase to unity,thus reducing the voltage stress across the output rectifier,and minimizing both the magnetizing inductance and the transformer bias current values. Moreover,to the auxiliary mosfet,the magnetizing current will negative,abolish the discontinuous conduction mode (DCM) of the basic Fly back and permits a smaller magnetizing inductance is to be selected. Besides,in contrast with the basic Fly back,the energy is supplied to th e secondary side not only from the magnetizing inductance,but also from the introduced series capacitor,minimizing the transformer energy necessity . The improved converter makes also the soft - transitions possible for both mosfet . For all these reasons,a s a more effective and compact size approximate,this topology shows better fulfillment s in high power density inexpensive applications. https://www.ijiert.org/paper-details?paper_id=141122