The present application discloses an impeller assembly and a mixing apparatus, and relates to the technical field of solid and liquid mixing devices. The impeller assembly includes an impeller structure and a housing structure. The impeller structure includes a body, and a surface of the body is provided with a plurality of backward-skewed blades. A blade angle of each backward-skewed blade on any flow plane first decreases progressively and then increases progressively from an inlet to an outlet. A first baffle is disposed on a lower portion of the body. The housing structure includes a second baffle. The first baffle is provided with first guide slots, and the second baffle is provided with second guide slots. A fluid enters from the inlet at an upper portion of the body, flows along the surface of the body, and flows out through the outlet at a lower portion of the body and through the first guide slots and the second guide slots. A centerline of each first guide slot is deflected towards a direction opposite to a rotation direction of the impeller structure, and a centerline of each second guide slot is deflected towards the rotation direction of the impeller structure. The present application solves the problems of unstable discharge, large vibration and noise, and insufficient work efficiency.