Objective： To investigate the biological characteristics of phage SM1 for stenotrophomonas maltophilia (Sm) and its effect in animal infection model. Methods： Phage SM1 isolated from raw sewage of hospital was identified by the plaque method.The morphology of phage SM1 was observed by electronmicrographics with negative staining.The extraction and electrophoresis of phage SM1 DNA were performed.Optimal multiplicity of infection，resistant mutation rate，one step growth curve and the effectiveness in animal models of phage SM1 were determined. Results： One Sm specific phage of myoviridae double-stranded DNA was identified，and named SM1.Electrophoresis of DNA demonstrated that the size of phage SM1 genome was about 50 kb.The growth curve of phage SM1 showed that the durations of incubation and burst period were 15 min and 50 min，respectively; and the burst size was 187.The resistant mutation rate of phage SM1 was 6×10^-10.All mice treated with phage SM1 survived after 7 d of infection with stenotrophomonas maltophilia. Conclusions： The phage SM1 has a relatively broad host range，a shorter incubation period，an apparent burst size and a lower resistant mutation rate.The therapy of phage SM1 for Sm infection in mice is effective.