The invention relates to a cleaning agent for a solar panel. The cleaning agent comprises the following components by mass percent: 10 to 30 percent of surface active agent, 10 to 30 percent of solvent, 0.5 to 5 percent of electrostatic resisting agent, 10 to 30 percent of antifreezing agent, 2 to 5 percent of softening agent and 5 to 20 percent of oil removing agent. The solar panel is conventionally cleaned manually and rinsed mechanically at present, and the traditional way for cleaning the solar panel has the weaknesses such as high labor cost, large workload, high risk, complexity in operation, halfway cleaning, short washing period and the like. The cleaning agent for the solar panel is strong in decontamination capacity, anti-electrostatic, wide in environmental applicability, good in stability, low-foam, nondestructive for the glass surface, free from peculiar smell, toxic-free, corrosiveless, inflammable, unexplosive and free from polluting the environment.