Laundry treatment agent storage and dispensing device, washing machine, and laundry treatment agent dispensing control method of washing machine

A laundry treatment agent storage and dispensing device comprises a storage device and a dispensing device which are integrally arranged. A storage cavity or box stores laundry treatment agent. The dispensing device has a hollow cavity, and a flexible separator is hermetically installed in the hollow cavity to divide the hollow cavity into a water inlet cavity and a liquid storage cavity. The liquid storage cavity has a liquid inlet end and a liquid outlet end; the liquid inlet end communicates with the storage cavity or box. Inlet water of the washing machine flows into/out of the water inlet cavity, the flexible separator is squeezed to deform towards the liquid storage cavity to enable the laundry treatment agent accommodated in the liquid storage cavity to be discharged through the liquid outlet end. The laundry treatment agent is stored and automatically dispensed by the storage device and the dispensing device.