This book constitutes the refereed proceedings of the 11th China National Conference on Big Data and Social Computing, BDSC 2026, held in Chongqing, China, during July 24–26, 2026. The 29 full papers presented in this volume were carefully reviewed and selected from 84 submissions. They organised in the following topical sections as follows : Theories and Foundations of Social Computing; Trustworthy Social Computing for Security and Fairness; Resilient Society and Resilient AI; Data Intelligence and Data Governance; Cross-Modal Social Computing and Applications.