The incidence of spondylolysis in adolescent accounts for about 3% to7% and its treatment,as reported in the literature, has not been consistent.we reported on a 17-year-old boy who underwent Staphylococcal Enterotoxin C injection guided by C-arm X-ray for L5 spondylolysis,his ODI score was significantly better than pretreatment and achieved bony union on X-ray and CT scan in 1-year follow-up, the treatment was worthy of being clinical spread for its economy、 convenience、 security and minimal invasion.