OBJECTIVE： To analyze fatty oil and volatile oil in seed of Metaplexis japonica. METHODS： Fatty oil and volatile oil in seed of M. japonica were analyzed by GC-MS： HP-5MS quartz capillary column， high purity nitrogen as carrier gas， flow rate of 1 mL/min， injector temperature of 220 ℃， primary column temperature of 120 ℃ （temperature programmed）， column pressure of 80 kPa， split sampling， split ratio of 20 ∶ 1， sample size of 1 μL. Mass condition： electron bombardment ion source， electron energy of 70 eV， interface temperature of 250 ℃， mass scanning range of m/z 50-550， scanning interval of 1.0 s. The difference of volatile components in seed of M. japonica before and after processing was analyzed by HSGC-MS： HP-5MS quartz capillary column， high purity nitrogen as carrier gas， flow rate of 1 mL/min， headspace heating temperature of 90 ℃， heating time of 30 min， primary column temperature of 80 ℃ （temperature programmed）， column pressure of 80 kPa， split sampling， split ratio of 20 ∶ 1， sample size of 1 μL. Mass condition： electron bombardment ion source， electron energy of 70 eV， interface temperature of 210 ℃， mass scanning range of m/z 50-550， scanning interval of 1.0 s. RESULTS： A totall of 30 components were identified in fatty oil， among which relative contents of linoleic acid， oleic acid， palmitic acid were in high level； 54 components were identified in volatile oil， main components were terpenes， among which relative contents of cananga oil diene， thujopsene， dehydro aromadendrene were in high level. Terpinen-4-ol was found and dihydrocarveol increased 100％ after frying，compared with before frying. CONCLUSIONS： The study basically confirm main component of fatty oil and volatile oil in seed of M. japonica； there is difference of volatile components in seed of M. japonica before and after frying.