A： S1: blanking, and generating a blank which have a ball joint and a connecting rod; S2:：The connecting rod of the blank is processed by wire rolling to form the first piece with thread S3: Cutting a second piece to at least remove the plating formed at the ball joint of the second piece ,then to form a third piece S4: cutting the second piece, at least removing the plating formed at the ball head of the second piece to form a third piece; S5: Roll and clean the third piece.