Objective: To clone and evaluate the virulence and protection of suilysin(SLY), for developing a vaccine against the infective Streptococcus suis type 2(SS2). Methods: Sly gene was amplified from a SS2 strain isolated in Ziyang, Sichuan, and ligased into T-vector, then transferred into a refined pGEX-6p1 without LacIq gene. Protein SDS-PAGE electrophoresis and hemolysis test was used to check the expression and activity of SLY. Results: The SLY expression of recombinant strain was lower by degree for growth at 5 h, 10 h and 15 h, and transparent ring around recombinant strain were observed in electrophoresis and hemolysis test respectively. Conclusion: Secreted SLY was expressed in early stage and exhibited a distinctive β-hemolysis activity.