Abstract: Alkaline phosphatase(AKP)is one kind of enzyme, which is not absolutely specific.It could hydrolise lots of phosphoric acid ester chemical compound in alkaline environment while the activator Mg2+and Mn2+are needed.It’s a high valuable tool enzyme1Itπs mainly used in studying nucleric acid, analysising nucleoticle sequences and the isolation, recombination of genes.The merchant reagent of AKP is very expensive1Comparing with activity of AKP in many species,we found that there is high activity in the viscera of Monopterus albus.So this paper mainly deals with isolating,purifying AKP from viscera of Monopterus albus,studying its characters and preparingfor its application1It was prepared and purified by means of the following techniques:n-butanol extraction,amonanium sulfate precipitation,ion exchange chromatography on DEAE2Sepharose Fast Flow column and gel filtration chromatographyon Sephacryl S22001The preparation was shown to be homogenous on polyacrylamide gel electrophoresis1The specific activity was 30.5 unit/mg protein1Its molecular weight was determined to be about 133.4 kD on gel filtration chromatography and submit is 66.8 kDon SDS2PAGE,so we speculate this enzyme has two submits1The kinetic characters of the enzyme have been studied1The optimum pH and optimum temperature for the enzyme to catalyze the hydrolysis of phenylphosphoric acid disodium salt are pH10.2 and 40 ℃,and this enzyme activity is not stable at high temperature and low pH,the Michaelis constant(Km)is 1.17mmol/L1The positive monovalent alkali ions(K+,Na+) have no effects on the activity of the enzyme ;Magnesium ion activates the enzyme activity and Zinc ion inhibit the enzyme activity.