Abstract: To prepare diclofenac sodium thermosensitive gel and investigate its release characteristics in vitro. The medicines were given with diclofenac sodium as main medicine，poloxamer 407 and poloxamer 188 as gel materials，polyethylene glycol 2000，polyethylene glycol 4000 and polyethylene glycol 6000 as osmosis promoter，the diclofenac sodium gel was prepared with cold cut method；the effects of different types of polyethylene glycol and proportion of gel materials on gelation temperature were investigated. In this paper，the percutaneous experiment of Franz diffusion pool and the UV method were used to investigate the releasing rule in vitro. The in vitro releasing results showed that with the gelation temperature at 32，34，36 ℃ environment，on preparation of diclofenac sodium into thermosensitive gel with addition of polyethylene glycol，the process could significantly increase the drug dissolution rate.

Key words: diclofenac sodium, thermosensitive gel, polyethylene glycol, in vitro release, gelation temperature