The utility model provides an among the aligning device is used in shaft coupling installation, a support piece is provided with the guiding hole and reaches the spread groove that feeds through with the guiding hole, the probe sets up in the guiding hole, and can follow the guiding hole and remove, all the moving direction with the probe is mutually perpendicular for a support piece's bottom surface and top reference surface, the probe has first scale section, the 2nd support piece sets up in the spread groove with sliding, and the slip direction is mutually perpendicular with the moving direction of probe, the elastic component links to each other with the probe to the elasticity of messenger its bottom surface and two support piece's top surface laminating is exerted the probe, under the bottom surface of probe and the roof of spread groove lay in the coplanar state, the first positive number scale district of first scale section and a support piece's top reference surface lay in the scale reading of coplanar, for this reason under the state support piece's bottom surface and the 2nd support piece's bottom surface in probe moving direction's interval. The great contradiction of installing between the operating space of needs when the size of equipment is more and more littleer install at the scene can be alleviated with the percentage table to above -mentioned scheme.