An improved structure of transformer's lead frame includes at least a lead frame module (1) consisting of a lead frame main body and a lead frame cover, the lead frame main body has a through hole (111) furnished at the center thereof; a bobbin (102) formed at the side of the circumference of the through hole, and a pair of oppositely configured and reversely salient extension parts (114, 115) furnished at sides of the circumference of the through hole, each of the extension parts is combined to the mid-section of the wire connecting seats (1041,1042) that have a plurality of wire connecting posts (85, 851), a plurality of clip indentations (123, 124) are furnished at intervals and at the mid-section of the edge of the two sides of the corresponding extension parts and at the positions covered by the width of the corresponding extension parts.