Abstract: In allusion to the problem of high fluorine content in the production of wet-process phosphoric acid（WPA） by di- hydrate method，the de-fluorination purification for WPA was studied.The existing forms of fluorine in wet process phosphoric acid was briefly described.The reaction principles and fluorine removal factors of 3 common de-fluorination methods：chemical precipitation de-fluorination，vacuum concentration，and steam stripping，in the de-fluorination process were analyzed. The influencing factors of the de-fluorination rate were further investigated according to the reaction principles of each method.It was of great significance for fine processing of WPA，and provided a broader thinking to solve the problems of deep de-fluorination purification applied in practical production.

Key words: wet-process phosphoric acid；existing forms of fluorine；reaction principle；de-fluorination rate