Objective: To understand the prevalence and trend of diet related behaviors among secondary school students in Shanghai, and to provide a scientific basis for developing appropriate health education strategies. Methods: Anonymous questionnaire surveys were conducted among 71 291 students selected by multi stage stratified cluster sampling method from junior high schools,senior high schools and vocational schools in Shanghai in the year of 2008,2012,2015,2017,2019. The questionnaire adopted was "Shanghai adolescent health related behavior questionnaire". Test for trend test were applied for the analysis of the prevalence of their dietary behaviors. Results: The proportion of middle school students nutritional status within the normal range in each survey year were 73.40 %, 72.60%, 68.06%, 68.73%, 67.53%, respectively, while the rate of overweight and obesity increased from 13.17% in 2008 to 23.73% in 2019. The proportion of "eating fried food" decreased significantly by year, from 12.05 % to 4.23% (male, APC=-7.94%, t =-4.33, female, APC= -9.29%, t=-7.71, P <0.05) respectively. And the proportion of "eating dessert" also decreased significantly by year, from 31.66% to 11.14% (male, APC=-8.41%, t =-6.37, female, APC=-8.67%, t=-6.96, P <0.05). In the five surveys, the percentages of healthy diet related behaviors of secondary school students were 12.81%-21.82%, no significant upward trend was observed in the whole( P >0.05). The proportion of diet-related behaviors of nutrition unbalance and easily leading to obesity decreased significantly from 35.47% to 17.00%(APC=-6.71%, t= -5.00 , P <0.05). The proportion of diet related behavior of nutrition unbalance and not easily leading to obesity increased significantly from 39.15% to 60.16%(APC=3.46%, t=6.18, P <0.05). Conclusion Overweight and obesity among secondary school students in Shanghai are increasing during the past decade, and the proportion of healthy dietary behaviors is low. The knowledge of rational diet should be publicized among these students in order to develop healthy dietary behaviors.