The square stirring device comprises a square stirring container and a stirring shaft, the stirring shaft is obliquely arranged in the stirring container, two right-angle areas which are oppositely arranged are arranged below the inner wall of the stirring container and are respectively a dead angle area and an installation area, and the lower end of the stirring shaft is connected to the installation area. A raised first inner wall is arranged in the dead angle area towards the stirring shaft, and the edge of the first inner wall is attached to the inner wall of the stirring container. According to the scheme, the stirring shaft is obliquely arranged, so that the mixing track of liquid is improved, the mixing uniformity of the liquid in the stirring container is improved, and the mixing efficiency is improved; due to the fact that the stirring track of the stirring shaft is cylindrical, mixed liquid is prone to being difficult to stir in a dead angle area below the stirring shaft, the first inner wall is arranged in the dead angle area, namely, an area difficult to stir in the square stirring container is removed, dead angles where the liquid is difficult to mix are reduced, and the liquid mixing uniformity is improved.