Abstract: Shewanella sp.NJ49 was cultured with 2216 E and manual seawater for enzyme study which play key role in procession of degradation of petroleum hydrocarbon.Extracellular enzyme,periplasmic and cytoplasmic fractions were extracted after osmotic shock.Efficacy of hexadecane degradation was compared through three enzyme and metabolize product was analyzed by GC and GC-MS.Four enzymes of different molecular weight (greater than 100 000,30 000 100 000,10 000 \sim 30000 and 5000 10 000,respectively) were collected by ultrafiltration and then determined and compared the enzymatic activity.The results showed that degradation rate of extracellular enzyme and periplasmic enzyme was above 60\% and less than 40\%,respectively,but capacity of degradation hexadecane of cytoplasmic enzyme was zero.Degradation enzyme of Shewanella sp.NJ49 was located extracellular and periplasmic emzyme;Hexadecanal and 1hexadecanol were the main products in the process of n -hexadecane degradation,It accomplished the preliminary degradation by the terminal oxidation.Relative molecular mass of Monooxygenase was 0.03\sim 0.1 million.