The biochemical properties of a V. parahaemolyticus bacterophage were investigated. The results show that when the bacterophage infects the V. parahaemolyticus, the optimum pH value is 8; the optimum temperature is 35℃.The bacterophage is inactivated quickly when treated with upper 60℃. Also the bacterophage is sensitive to ultraviolet radiation and resistant to aether and chloroform. The incubation period of the V. parahaemolyticus has great effects to the bacterophage's bacteriolysis proportion. In Log phase, the bacterophage infects the V. parahaemolyticus easily. However the aged V. parahaemolyticus is resistant to bacterophage's infection. It's favorable to the bacterophage attaching to the V. parahaemolyticus when Ca²⁺ or Mg²⁺ was added into the culture medium. The ability of lysis of the bacterophage is strongest when the salinity of the water is about 20. The best multiplicity of infection is 0.1～1.0.