The multimedia simulation teaching mode introduces students into virtual scenes for learning. Whether it is enhancing students' interest in learning or enhancing their physical fitness, it is a new teaching mode. This article discusses the establishment of a BP neural network model to study the prediction of students' physical fitness and conducts experiments on predicting and evaluating adolescent physical fitness. The results indicate that the BP neural network model better reflects the functional relationship between various indicators of student physical fitness and the total test score, providing a more reasonable mathematical model for evaluating adolescent physical fitness.