A strain of bacteria XXG was isolated from rice fields irrigated from Taihu Lake. The bacterial genus was determined by analyzing its morphological characteristics, physiology biochemistry experiment and 16SrDNA sequence. Single factor test was conducted on the addition ratio of medium, the volume ratio of bacteria to algae, the density of bacteria and density of algae to study the effect of each factor on the effect of lysing algae. Box-Behnken Design (BBD) was used to design three major factors, namely, temperature (X1), pH (X2) and shaker speed (X3), to optimize the environmental factors that affect the lysing rate of algae. The method of lysing algae was initially examined by comparing the effect of bacterial weight suspension and sterile fermentation liquid on algal liquid. The experimental results showed that the similarity degree between XXG and Paenibacillus sp. KU573975 was 99.27%, and was initially identified as Paenibacillus. When the optimum volume ratio of bacterial to algal was 5.6%, the lysing rate of XXG bacteria to Microcystis aeruginosa solution at the early logarithmic growth stage reached at 77.1% after 6 d. Three important environmental factors that affected the efficiency of XXG algal lysing had a cross effect. The quadratic regression model of lysing rate of algae with the temperature, pH and shaker speed was established with P<0.0001 and R2 was 0.9727. Under the optimal algae-lysing characteristics, the lysing rate of algae was the highest when the temperature was 30℃, the pH was 7.5, and the shaking speed was 150 r/min, and the lysing rate of algae was up to 92.02%. Aseptic fermentation liquid without algal bacterial still had algae-lysing effect. It was speculated that the main algae-lysing processing of XXG bacteria was indirect effect. The reduction in algae-lysing effect produced by aseptic fermentation liquid compared with bacterial fermentation liquid may be achieved by the bacteria in bacterial fermentation liquid continuing to secrete some algae-lysing active substances.