The invention provides a whole four-dimensional high-precision adjusting device for grating splicing, and belongs to the technical field of adjusting devices of the grating splicing. The whole four-dimensional high-precision adjusting device for the grating splicing solves the problems that an existing grating posture adjusting device is low in driving and system rigid and poor in whole stability. A deflection adjusting assembly is located above a pitching plane interior assembly, a deflection adjusting base plate of the deflection adjusting assembly is fixedly connected with a deflection bracketing frame of the pitching plane interior assembly, and the pitching plane interior assembly is located above a translation driving assembly. An outer frame assembly is fixedly connected with a first translation guide rail connection plate, a second translation guide rail connection plate, a third translation guide rail connection plate and a fourth translation guide rail connection plate. A translation driving bending plate is fixedly connected with the outer frame assembly. Combination adjustment of four freedom degrees of the whole grating is achieved by adopting of a three-layer structure, and the problem that the height of a grating adjusting frame is limited is solved. By adopting of a flexible driving manner, all freedom degrees have a large movement range. The whole four-dimensional high-precision adjusting device has the advantages of being compact in structure, high in adjusting precision, strong in stability and the like.