The invention discloses a bending device for cylindrical diode pins. The bending device for the cylindrical diode pins comprises an inclined conveying grooved rail. A roller is inserted into the lower end of the conveying grooved rail. A circular arc notch is formed in the outer wall of the roller. Cushion blocks are formed in the positions, on the two sides of the notch, of the side wall of the conveying grooved rail. Connection blocks are fixed to the cushion blocks, and stop dogs are formed at the lower ends of the connection blocks. Annular cover bases are formed at the lower ends of the stop dogs. The roller is fixed to a rotary shaft in an inserted mode. The two ends of the rotary shaft are hinged to the cover bases correspondingly. One end of the rotary shaft extends out of the corresponding sleeve base and is fixedly provided with a drive gear in an inserted mode. The bending operation of the diode pins is achieved in a mechanical mode instead of a manual bending operation mode, accordingly, the production efficiency is effectively improved, and consistency of the bending lengths of the pins at the two ends of diodes can be ensured.