The invention belongs to the technical field of metal surface treatment, and particularly relates to a trivalent chromium hard chromium electroplating solution and application of the trivalent chromium hard chromium electroplating solution in hard chromium electroplating. The electroplating solution is prepared from trivalent chromium main salt, a carboxylic acid or carboxylate complexing agent, a buffering agent, conducting salt and a catalyst. The deposition velocity reaches 2.5 micrometers/minute or above, the current efficiency reaches 36% or above, the thickness of an electroplating layer can reach 150 micrometers or above, each liter of the electroplating solution can be used for performing continuous electroplating for 900 ampere hours (an additive is supplemented during the process), high efficiency and high stability are maintained, the hardness of the electroplating layer reaches HV950 or above, and the electroplating layer has wear resistance the same as or similar to that of hexavalent chromium, has large binding force with steel, copper and copper alloy and is free of peeling or stripping or cracking in a 300 DEG C thermal shock test. As nanometer materials are added, corrosion resistance lasts for 150 h or longer in a neutral salt spray test. The trivalent chromium hard chromium electroplating solution has broad application prospects in the fields of rollers, hydraulic components, printing cylinders, shock absorbers, coal mine hydraulic supports and the like.