The effective participation of peasants can raise the quality of high-standard farmland construction (HSFC) in China. How to avoid inefficient participation is an urgent issue that needs to be solved in the field of HSFC. However, the factors that influence peasants’ effective participation in the HSFC remains to be further studied. This study used factor analysis and a comprehensive evaluation method to calculate social networks and the level of peasants’ effective participation in HSFC based on a survey dataset of 347 peasants in Yancheng City, China. The influence of information support, incentive support, constraint support, network interaction, network trust, and network norms on the level of peasants’ effective participation in HSFC was analyzed using an ordered logistic model. The results of the study indicate that: (1) The overall level of peasants’ effective participation in the HSFC is at a “medium” level, and the level of peasants’ effective participation needs to be further raised. (2) Government support considerably influences peasants’ effective participation in HSFC. Information support, incentive support, and constraint support significantly impact peasants’ effective participation in HSFC. (3) Social networks possess a significant positive impact on the level of peasants’ effective participation in HSFC, with the core variables contributing to peasants’ effective participation in the order of network interaction, network trust, and network norms. (4) Peasants’ cognition significantly impacts peasants’ effective participation in HSFC. Therefore, to enhance the level of peasants’ effective participation in HSFC, it is suggested to further improve government information support, incentive support, and constraint support; strengthen network interaction, enhance network trust, improve network norms, and effectively play the role of social networks; and to strengthen peasants’ education and training.