Protection device and method for partial sand blowing and nitriding of part

The invention discloses a protection device and method for partial sand blowing and nitriding of a part. The protection device comprises a base and a protection cover. The base comprises an annular plate and an annular boss integrally formed on the annular plate. The annular boss is used for being inserted into a lower hole section of a stepped hole of a part to be subjected to sand blasting, and the top end of the annular boss abuts against the inner stepped face of the part to be subjected to sand blasting. The protecting cover is provided with a stepped through hole, and a first step surface is formed in the stepped through hole; the protecting cover is used for being connected to the part to be subjected to sand blasting in a buckled mode, the top end of the part to be subjected to sand blasting abuts against the first step face, and the bottom end of the protecting cover abuts against the top face of the annular plate. The protection device is adopted in the part local sand blowing and nitriding method.