The most suitable enzyme which was used to extract palm oil from the palm fruit was selected among seven kinds of common hydrolase，such as cellulase, hemi-cellulase, pectinase, acid protease and so on. The optimal parameters were obtained based on single factor and orthogonal test, and acid value of palm oil was determined as well. The results showed that cellulase was the best enzyme to extract palm oil, and there was no significant influence of pH and temperature on the yield of palm oil. The optimum extraction conditions by cellulase was pH 4.5, temperature 45 ℃, hydrolysis time 2.5 h, the ratio of solid to liquid 1∶2 g/mL and enzyme dosage of 2%. The extraction rate of oil under this condition was 46.90%, and the acid value was 6.01 mg/g KOH. The results can provide reference for the industrial preparation of palm oil.