Adolescence is the preparatory stage for young people to enter the society. Although teenagers are good at catering to the development trend of society, they are limited by age, growth environment, and other factors, and their cognition of society is too simple, resulting in poor social adaptability. This paper adopts control method and questionnaire survey to study the effect of mental health education on improving social adaptability of teenagers. A total of 712 adolescents from two schools in Beijing were selected for the study (
M
=
15.76
,
SD
=
2.338
). In addition, the age, gender, family environment, and growth environment of the youth were taken as the independent variables. The results showed that the social adaptability of adolescents and its subdimensions were significantly affected by age, family environment, and growth environment (
p
<
0.05
), while gender had little effect on the overall social adaptability of adolescents (
p
>
0.05
). After receiving mental health education, adolescents’ social adaptability has significantly improved, with statistical differences in self-adjustment ability, interpersonal adaptability, behavioral adaptability, and environmental adaptability as well as in all dimensions (
p
<
0.01
), indicating that mental health education has obvious and comprehensive improvement effect on adolescents’ social adaptability. The social adaptability of adolescents is also affected by their own characteristics and growth background, which will further affect the effect of mental health education on the improvement of the social adaptability of adolescents. Based on these findings, this study provides significant insights for parents and teachers to improve the social adaptability of adolescents from the angle of mental health. Meanwhile, parents and teachers should specially pay attention to the influence of personality and growth background of adolescents which also play a decisive role on the effect of mental health education. This study provides practical and useful recommendations for improving adolescent social adaptability and adds to the theory for corresponding future research.