Objective To investigate the impact of genetic and environmental factors on mental health status and to estimate the prevalence of subclinical psychiatric symptoms and psychological problems in child and adolescent twins, by using the Strengths and Difficulties Questionnaire (SDQ). Methods A total of 59 pairs of twins aged 6-16 years were recruited with support from educational committees and schools. After the guardians of these twins had signed an informed consent form, SDQ were completed by the parents and teachers of these twins to investigate their mental health status. Buccal mucosa samples were collected from all twins for DNA extraction and zygosity identification test. Results The intrapair correlation coefficients of monozygotic twins were significantly different from those of dizygotic twins in terms of emotional symptoms, inattention-hyperactivity, peer problems, impact and diagnostic predictions (including any psychiatric disorder, emotional disorder, oppositional/conduct disorders, ADHD/hyperkinesis). The results from the SDQ screening questionnaire showed that up to 37.5% of the studied twins were suffering from a psychiatric disorder, including emotional disorder (5.5%), oppositional/conduct disorder (29.7%), and ADHD/hyperkinesis (14.8%).Conclusion Genes plays an important role in the mental health status of child and adolescent twins. More attention should be paid to the mental development and mental health in these twins, because of the considerable prevalence of subclinical psychiatric symptoms and psychological problems.