Objective To comprehensively investigate the mental health status of Chinese primary school students over the past 20 years.Methods A Meta-analysis was conducted on 106 surveys using the Mental Health Test(MHT)for primary school students(n= 67,382).Results The mental health scores of primary school students were less than 8 points for various factors.Learning anxiety,loneliness,and self-blame tendencies increased over the years(R2=5%,6%,10%;Ps<0.05),while interpersonal anxiety,tendency towards terror,and impulsive tendencies decreased over the years(R2=5%,6%,10%;Ps<0.05).The study found that left-behind primary school students had slightly higher mental health scores than non-left-behind students(d:0.26~0.39,Ps<0.05).Additionally,children of rural migrant workers had slightly higher scores in learning anxiety,interpersonal anxiety,loneliness,and tendency towards terror compared to local primary school students(d:0.28~0.37,P<0.05).Conclusions The mental health status of primary school students is generally positive,but changing trends over the years have mixed implications.Research indicates that left-behind primary school students and children of rural migrant workers have relatively poorer mental health.Differences in research findings may be influenced by the age and type of students.