Ozonization processes of 15 tetracosenoic acid methyl ester(TAE) and 9 octadecenoic acid methyl ester(OAE) obtained from Malania Oleifera Chum oil have been monitored by combined gas chromato graphy mass spectrometry(GC MS) or gas chromatography(GC). The effect of reaction temperature and solvent( heptane , toluene, n butyl acetate, ethanol, and heptane ethanol) on the ozonization selectivity of TAE and OAE were investigated. The results show that TAE has good selectivity in heptane because of its small dielectric constant. The k TAE / k OAE of the ozonization reaction decreased with the increase of ethanol in heptane ethanol , whereas the ozonization selectivities of TAE and OAE reduced with the increase of the reaction temperature .