According to theory, students' implicit theories of ability can affect their motivation and engagement in physical education (PE). Limited research has been conducted to examine the relationships between implicit theories of ability and motivation and engagement among K-12 students in PE. Our study examined the relationship between implicit theories of ability and perceived enjoyment in PE, and explored whether there were any gender differences in implicit theories of ability and perceived enjoyment in PE. A package of surveys was administered to 252 Chinese 12th graders. Data were analyzed using confirmatory factor analysis, correlations, and MANOVA. Chinese 12th grade participants endorsing higher incremental views in ability were likely to enjoy PE more. Male participants showed stronger beliefs in incremental views and enjoyed PE more than females. It was suggested that PE teachers may be able to enhance students' enjoyment by focusing on incremental views. This is, ability in sports can be increased dramatically by effort and hardworking.