ipunculus nudus Linnaeus at an average body weight of 39.20±0.24 mg were divided into 9 groups with triplicates and 500 larvae in each replicate to investigate the effects of dietary protein level on growth performance and body composition of juvenile peanut worm, S. nudus, by feeding diets with 9 protein levels (25.21%, 29.87%, 35.03%, 40.67%, 45.47%, 50.12%, 55.29%, 60.38%,and 64.85%) for 8 weeks. The results showed that protein level significantly affected growth performance of S. nudus larvae (P<0.05). With the increasing dietary protein level, the weight growth ratio (WGR) and specific growth ratio (SGR) firstly increased and then decreased, and when the dietary protein level was 45.47%, both WGR and SGR produced the maximum value. The regression model analysis showed the best dietary protein level was 46.79%,at which the best WGR was acquired. The results of body composition analysis showed that dietary protein level had significant effects on body protein content (P<0.05), which increased with the increasing doses of dietary protein. S. nudus fed with 64.85% protein produced the highest body protein content, and was significantly different from the groups with other protein levels (P<0.05). There was a downward trend in body lipid content, and when the dietary protein level was 64.85%, the body lipid content was significantly lower than that in groups with 25.21%, 29.87%, 35.03% and 40.67% protein (P<0.05). The dietary protein level had no significant effects on body ash content (P>0.05). Based on comprehensive analysis of WGR, it was concluded that the suitable dietary protein level for S. nudus larvae should be 46.79%.