The invention provides a trivalent chromium electroplating solution of a sulfate system. The trivalent chromium electroplating solution is characterized by comprising the following components in molarconcentration (mol/L): chromium sulfate0.2-0.6, potassium sulfate 0.5-1.5, ammonium bromide 0.02-0.5, boric acid 0.5-1.2, sodium hypophosphite 0.1-1, ferrous sulfate 0.01-0.1, complexing agent 0.2-2.0, thickening agent 0.01-0.5 and the balance of water. The invention also discloses an electroplating method for the electroplating solution. Compared with the prior art, the electroplating solution and the electroplating method have the advantages that: the electroplating solution is clean and pollution free, the thickness of the plating layer reaches 20 to 80mu m, the plating layer is smooth with few cracks and high bonding force, the source of raw materials is rich, the cost is lower, the performance-to-price ratio is good, the electroplating solution can be continuously used for electroplating for 0.5 to 5 hours, the hardness of the plating layer is 600 to 700HV, and after thermal treatment, the hardness of the plating layer can reach 1,200HV.