Based on a questionnaire survey of metallurgical engineering undergraduates with at least one complete subject competition experience in Hebei University of Engineering, the general features of undergraduates' learning engagement and learning gains were studied. The impact of metallurgical engineering undergraduates' subject competition engagement on learning gains was analyzed. The results showed that the more the undergraduates take part in the subject competition, the greater the undergraduates gain; the more the undergraduates interact with others,the greater the undergraduates gained. To better improve students' learning gains, we should pay more attention and further support undergraduates' subject competition, and improve the guarantee system of subject competition guidance.