Abstract: OBJECTIVE To establish the determination method for mannitol in Periplaneta americana from different field breeding. METHODS The content of mannitol in Periplaneta americana was determined by UV spectrophotometry at detection wavelength of 412 nm with mannitol as standard substance. RESULTS The contents of mannitol were different in Periplaneta americana from different field breeding, and the contents of mannitol were different in Periplaneta americana in different batches which came from the same field breeding. CONCLUSION The method is simple, accurate, reproducible and can be used for determination of mannitol in Periplaneta americana.