Cleaning liquid for regenerated SCR (silicon controlled rectifier) denitration catalyst and method for regenerating SCR denitration catalyst

The invention provides a cleaning liquid for a regenerated SCR (silicon controlled rectifier) denitration catalyst. The cleaning liquid can treat an inactivated catalyst, so that the denitration performance of the catalyst can be recovered; the waste solid pollution is relieved, and the running cost of flue gas denitration engineering of a coal-fired power plant can be reduced. The cleaning liquid comprises the following components in percentage by weight: 0.1-1 percent of a penetration enhancer JFC, 0.1-1 percent of an emulsifier OP-10, 0.1-1 percent of a leveling agent peregal O, 1-10 percent of a sulfuric acid, 0.5-5 percent of vanadyl sulfate, 1-5 percent of ammonium metatungsten, 0.1-1 percent of a corrosion inhibitor and the balance of water; the total mass percentage of all the substances is 100; the substances are mechanically stirred after being mixed for 20-30 minutes, so that the cleaning liquid is obtained.