Abstract: A bacterial alginate lyase-producing strain B1 was screened with transparent circle method,It was identified as Pseudoalteromonas sp. according to its morphological observation and 16 S r DNA sequence analysis to identified strain B1.And by single-factor method to optimize its enzyme production conditions,the optimal medium component were,sodium alginate 1%,NH4 Cl 0.2%,Na Cl 3%,KH2PO40.02%,Mg SO40.01%,Ca Cl2·2H2O 0.1%,initial p H5.5,the optimal culture conditions were as follows :75 m L medium in 250 m L Erlenmeyer flask,Cultured at 30 ℃,shaking speed of 180 r/min,for 22 h. Under the optimal culture conditions,the highest enzyme activity of alginate lyase was up to 71.94 U/m L,improving 72.11%.