The invention discloses a debris-free die-cutting method for a thickness area on a lead frame. The debris-free die-cutting method comprises the following steps of: pre-stamping the lead frame througha stamping die, thinning and precisely cutting and stamping to form a water drainage ditch, wherein the upper width dimension of the water drainage ditch is greater than the lower width dimension of the water drainage ditch, the upper side wall thickness of the water drainage ditch is greater than the lower side wall thickness; after die-cutting and forming the water drainage ditch, enabling a debris-free die-cutting punch arranged on an upper module to be matched with a debris discharge hole which is formed in a lower module and is adaptive to the debris-free die-cutting punch up and down fordie-cutting and forming mould cavities at the front side and the rear side of the water drainage ditch; during mould cavity die-cutting, enabling a die-cutting flange arranged at the inner side of the debris-free die-cutting punch to die-cut debris which is extruded towards the lower side wall of the water drainage ditch from the upper side wall of the water drainage ditch, discharging the debristhrough a debris discharge hole, completely cutting off debris, thereby achieving the thick and thin material debris-free die-cutting purpose. The debris-free die-cutting method can increase the qualification rate of products, further can improve production efficiency to quicken production progress of production enterprises, meets increasingly strained needs, and is beneficial for promoting further development of information technology.