The utility model discloses an acid feeding device of a spinning machine. The acid feeding device comprises an acid bath head tank (1) communicating an acid station and a bath of the spinning machine, wherein the acid bath head tank (1) comprises an acid inlet hole (2) where an acid bath acid feeding pipe is arranged and an acid outlet hole (4) where a main acid feeding pipe (3) is arranged, and the acid station is communicated with the acid inlet hole (2) of the acid bath head tank (1) through the acid bath acid feeding pipe; an inlet end of the main acid feeding pipe is connected onto the acid outlet hole (4), and more than two outlet ends of the main acid feeding pipe are communicated with the bath of the spinning machine. The acid feeding device is simple in structure and reasonable in design, overcomes the defect that a conventional acid feeding device of the spinning machine adopts an adjusting valve to control fluctuation of the acid bath and has the characteristics of uniformity of acid feeding of the spinning machine and reduction of fluctuation of the acid bath, the product quality is improved while the production stability of viscose staple fiber is guaranteed, and the actual use effect is excellent.