The invention relates to a low-temperature slag removal agent which belongs to a fusion agent for casting. Aiming at the traditional slag removal agent for removing slag of melts in a casting process of aluminum and aluminum alloy, a slag removal process can be carried out only when the melt temperature reaches 710-720 DEG C, and casting operations can be carried out only when the treated melts are cooled to 680-690 DEG C, thus energy waste and meaningless working hour increase are caused. A remedial method of adding new aluminum and aluminum alloy ingots is also adopted, but the problem that the added new ingot melts are not refined and deslagged is brought. The low-temperature slag removal agent comprises the following components in percentage by weight: 10-20 percent of sodium nitrate, 5-15 percent of sodium fluoride, 10-20 percent of calcium fluoride, 5-15 percent of potassium chloride, 15-25 percent of sodium sulfate (anhydrous sodium sulphate), 3-7 percent of carbon dust and the balance of sodium chloride. Proved by tests, effective slag removal treatment can be carried out when the temperature of the casting operations reaches 680-690 DEG C, and the requirement that slagging can be achieved only when the temperature is 710-720 DEG C in the prior art does not need to be met. Compared with the prior art, the invention not only saves energy, but also shortens working hours.