This book constitutes the thoroughly refereed post conference papers of the Second International Conference on Blockchain and Trustworthy Systems, Blocksys 2020, held in Dali, China*, in August 2020.The 42 full papers and the 11 short papers were carefully reviewed and selected from 100 submissions. The papers are organized in topical sections: theories and algorithms for blockchain, performance optimization of blockchain, blockchain security and privacy, blockchain and cloud compu...