A clothing treatment agent dispensing assembly for use in a clothing treatment device, and a clothing treatment device, the clothing treatment device including a body, the clothing treatment agent dispensing assembly including a dispensing container and a storage container in sealed connection to one another, the vertical cross-section of the dispensing container being smaller than the vertical cross-section of the storage container, and the dispensing container and the storage container both being capable of sliding relative to the body, such that when the dispensing container is pulled out of the body, the storage container can follow the dispensing container to slide in the body. The present clothing treatment device is more flexible in the layout of the overall space, such that the layout and installation of components such as a control panel are more flexible, facilitating product design.