An automatic dispensing system for a washing machine, and a washing machine. The system comprises: a water box (1001), on which a main water inlet pipe and a detergent dispensing pipe are integrated; a distribution box (1002) provided in the water box (1001), at least one mounting cavity used for placing a detergent additive box (1) being provided in the distribution box (1002); the detergent additive box (1) provided with a one-way ventilation structure (2) and a liquid outlet (12), the detergent additive box (1) being mounted in the mounting cavity, the liquid outlet (12) being opened when the detergent additive box (1) is communicated with the detergent dispensing pipe, and the liquid outlet (12) being closed when the detergent additive box (1) is disconnected from the detergent dispensing pipe; and a negative pressure pumping mechanism, comprising a Venturi tube in the main water inlet pipe, the liquid in the detergent additive box (1) is pumped and dispersed into a washing tub by means of detergent dispe
