Abstract: Internet expansion in rural areas provides a new technological empowerment for rural residents' social capital accumulation and dietary quality improvement. Based on a micro-survey data of 316 rural households in Heilongjiang Province and applying the information effect theory and the social capital theory, this paper analyzes the microscopic effect of internet use on the dietary quality of rural residents and explores the mediation effect of social capital by the OLS model and the mediation effect model. Results show that the dietary quality of rural residents in Heilongjiang Province is in a state of low dietary imbalance, and the dietary quality distance is 34.133 from the mean. Internet use can significantly improve the dietary quality of rural residents and can have a positive impact on the dietary quality of rural residents through the partial intermediary effect of social capital. Heterogeneity analysis shows that the effect of internet use on improving the dietary quality of rural residents is more significant among groups with higher education and larger planting scales. Based on the above analysis results, this paper suggests: solidly promoting reasonable dietary actions to enhance balanced dietary nutrition for rural residents, developing the "Internet + Nutrition and Diet" model vertically, expanding new channels for rural residents to socialize on the internet, and increasing the stock of social capital.