Previous studies have shown that green space has a potential role in reducing the risk of overweight and obesity of surrounding people, but its specific effectiveness needs to be determined. The purposes of this study are to quantitatively evaluate the published studies on green space and residents" overweight and obesity and to explore the impact of differences between the studies on the results, and make specific recommendations for further research. Based on the meta-analysis, we systematically searched the relevant literature before November 2020 in the Web of Science database and the PubMed database and selected the literature according to the established inclusion criteria. The methodological quality assessment was based on the Agency for Healthcare Research and Quality (AHRQ) and the Newcastle-Ottawa Scale (NOS). Finally, 69 studies on green space and residents’ overweight and obesity were included. We combined the effect sizes above according to the type of outcome variables and divided the research into different subgroups based on study design (cross-sectional studies and cohort studies), measurement of greenspace exposure, participants" age, and geographic analysis unit to find differences in the impact of the results. Our meta-analytical results showed that: ① There is a negative relationship between green space and overweight or obesity risk, body mass index (BMI), and waist circumference, but the results of different study designs are quite different. ② Results of combined effect sizes are inconsistent and mixed across different green space measurement studies. Vegetation coverage is significantly related to lower BMI, overweight, and obesity risks. Accessible green space nearby is good for alleviating obesity. The number of green spaces nearby is conducive to reducing the risk of obesity, but there are no relationships between the proximity and area of green spaces and obesity-related indicators. ③ Compared with children and adolescents, there is a stronger relationship between green space and overweight and obesity of adults. ④ The relationship between green space and residents" overweight and obesity has a significant scale effect, and the results obtained by using geographic analysis units with different scales are not consistent. The farther green space has weakened the effect on reducing the probability of residents" overweight and obesity. The results of the meta-analysis show that the relationship between green space and residents’ overweight and obesity is mixed in the subgroup analysis, which means that their relationship may be more complex. These remind us: more longitudinal studies should be conducted in this field to further explore the causal relationship and mechanism between them. In addition, constructing a complete green space measurement index system, considering complex and multi-scale geographic analysis units, and avoiding ignoring the influence of various confounding factors from participants, will enable future research to draw clearer conclusions and provide a scientific basis for urban green space system planning and related policy-making.