Objective To investigate the impact of genetic factors on mental health status in child and adolescent twins. Methods A total of 102 pairs of twins aged 6 to 16 years were recruited with the support from educational committees and schools. After the guardians of these twins had signed an informed consent form, the Chinese version growth and the state of health evaluation (Development and Well-Bing Assessment, DAWBA) were completed by the parents of these twins to investigate their mental health status. Buccal mucosa samples were collected from all twins for DNA extraction and zygosity identification test. Result A total of 102 pairs of twins were recruited, among whom 93 pairs finished the investigation, including 50 monozygotic pairs and 43 dizygotic pairs. The results of emotional symptoms and behavior symptoms and the impact of symptoms from the DAWBA screening questionnaire showed that the intrapair correlation coeficien of the emotional disorder and the oppositional/conduct disorder and the impact in monozygotic twins were more remarkable than those in dizygotie twins, including separation anxiety (MZ group correlation coefficient (r) = 0.821, Plt;0.01; DZ group r=0.348, Plt;0.01), generalized anxiety (MZ group r=0.546, Plt;0.01; DZ group r=0.309, Plt;0.01), a special terror symptoms (MZ group r=0.849, Plt;0.01; DZ group r=0.726, Plt;0.01 ), and oppositional defiant / conduct disorder (MZ group r=0.237, Plt;0.01; DZ group r=0.163, Plt;0.01), attention deficit - hyperactivity disorder (MZ group r=0.640, Plt;0.01; DZ group r=0.198, Plt;0.01), autistic symptoms (MZ group r=0.680, Plt;0.01; DZ group r=0.372, Plt;0.01). Conclusion Genetic factors play an important role in mental health status of child twins.