Abstract: According to the statistical data of catch, fishing effort, as well as rainfall, wind speed and salinity about Guangxi during 1949~1985, the effect of the natural environment variation on annual change of Guangxi catch has been analyzed. It is difficulty to be transformed for the fishing effort, so the time series has been adopted, then the regression model of catch to fishing effortand the environment variables has been established to reflect the variation of fishery resources in Beibu Gulf. The analysis result indicates the fluctuation of catch has not only remarkable related with fishing effort, but also with average rainfall of Guangdong coast, average rainfall of Beibu Gulf coast, Weizhou Island salinity as well as Hong Kong monsoon. The regression coefficient inthe model of time series and environment variable is 0.93,and the confidence level is above 99%. The results show that the effect of variation of environmental factor on the fluctuation of fishery resources in Beibu Gulf besides the fishing element is remarkable.