Selection with stirring, heating andd bottom row soap stainless steel or glass-lined reactor alkali refining kettle complete alkali refining process, biodiesel low viscosity, in order to improve the heat transfer and speed up the reaction, increase the heating plate heat exchanger with an outer loop, according to alkali refining kettle and add maximum volume to determine the maximum amount of lye into the oil from circulating heating thermostat to 60 ~ 65 ℃, stirring and adding lye from the cycle turned, sustained 30min, make lye sufficiently dispersed participation and the reaction was stirred after closing and self-cycle, natural settling.