The invention discloses an acid washing system of low-temperature multi-effect seawater desalting equipment. The acid washing system comprises an acid tank, an acid feeding pump, a cleaning header pipe, a cleaning solution inlet valve, a sprayer, an inter-effect communicating pipe, a saline discharge pipeline and a saline discharge pump, wherein the acid tank is connected with the cleaning header pipe through the acid feeding pump, and the sprayer of an evaporator of each effect is connected in parallel to the cleaning header pipe through respective cleaning solution inlet valve. The system realizes respective cleaning of each effect, achieves good descaling effect on the effect to be cleaned, reduces the acid washing expense, prevents over acid washing from corroding a heat exchange pipe of the low-temperature multi-effect seawater desalting equipment, and prolongs the service life of the heat exchange pipe.