Abstract: Yunnan Chemical Research Institute of Chemical Industry has developed a process in producing high concentration formic acid from the reaction of PPA and the sodium formate which is a by-product of the phosphorus tail gas.In allusion to the specific system to get formic acid，the separation technology was studied.Several methods，such as reduced pressure distillation，disk evaporation，microwave evaporation，spray drying，and flash evaporation，were compared to confirm which is more suitable for this system.Through studying the evaporation intensity and the formic acid product concentration in different methods，these methods except the flash evaporation all could realize the separation continuously.But after comparing the data of the methods mentioned above，the more proper separation method was the spray drying.

Key words: phosphorus tail gas, formic acid, separation technology