The invention provides an unstable flow guiding device for a pump. The unstable flow guiding device for the pump comprises a plurality of inlet flow guiding grooves, a plurality of middle flow guidinggrooves and a plurality of outlet flow guiding grooves; an area between a shell and an impeller body is arranged into an impeller flow channel; the inlet flow guiding grooves each comprise a main pipeline and a front end backflow pipeline; each main pipeline is located at the position of the edge of an inlet of the impeller flow channel; one end of each front end backflow pipeline is connected with the main pipeline; the other end of the front end backflow pipeline is communicated with a pump cavity; any middle flow guiding groove is in the shell, and is located on the middle portion of the impeller flow channel; an outlet flow guiding groove is in the shell, and is located at the outlet position of the impeller flow channel; and the inlet flow guiding grooves, the middle flow guiding grooves and the outlet flow guiding grooves are uniformly distributed in the radial direction of the center line of the axis. By means of the unstable flow guiding device for the pump, influences of existence of blades on main flow can be reduced, the phenomena of backflow, vortexes and the like generated at different positions in the flowing process can be effectively improved, and the flowing efficiency is greatly improved.