Objective To identify the status of mental health among left-behind children and related factors in underdeveloped areas of Guangdong province. Methods In this descriptive study,a total of 268 children aged 10~17 years old in the areas were selected by cluster sampling.The Strengths and Difficulties Questionnaires (the edition for students,SDQ) was used to measure status of mental health of children. Results 10% of left-behind children experienced emotional symptoms,16.5% had conduct problems,11.4% exhibited hyperactivity/inattention,12.7% had peer relationship problems and 12.7% had prosocial behaviors.The prevalence of conduct problems,hyperactivity/inattention and prosocial behaviors among left-behind children were significantly higher than those among non-left-behind children (P<0.05).Results from multiple Logistic regression analysis showed that parents not coming back to visit their children often (OR=6.18,95%CI:1.19~32.20) and children studying in boarding schools (OR=5.56,95%CI:1.13~27.40) might predicted higher prevalence of emotional problems.Male (OR=5.03,95%CI:1.38~18.39),boarding (OR=6.33,95%CI:1.20~33.56) and not contacting with parents often (OR=3.67,95%CI:1.08~12.42) were risk factors to hyperactivity/inattention.Children left behind less than 4 years (OR=3.90,95%CI:1.40~10.82) had higher prevalence of peer relationship problems.Children aged between 13~15 years old (OR=18.94,95%CI:2.11~170.16) and not used to pouring out (OR=9.82,95%CI:2.14~45.17),doing less sport (OR=10.25,95%CI:2.08~50.44) and contacting with their parents less frequently (OR=5.79,5%CI:1.20~27.83) predicted higher prevalence of prosocial behavior. Conclusion The prevalence of emotional and behavioral problems is high among left-behind children living the underdeveloped areas of Guangdong Province.