Study of “On Practice” and “On Contradiction” is part of our publishing house’s “Mao Zedong’s Classic Works Study Series.” Originally published in 2013 by the China Democracy and Legal System Publishing House, the author revised the manuscript in light of current social and historical contexts for this new edition. On Practice and On Contradiction are representative works on Marxist epistemology. The author employs Marxist epistemological viewpoints to expose dogmatism and empiricism within the Party, particularly the subjective errors of dogmatism. By applying dialectical materialism, the author summarizes the practical experiences of the Communist Party of China in leading China's revolutionary struggles, providing a profound explanation of the law of the unity of opposites. This book offers a meticulous interpretation of On Practice and On Contradiction based on the original texts, including their writing background, composition process, structure, content, viewpoints, historical impact, and contemporary significance. In addition to presenting the original text, the book expands on the philosophical ideas embedded in these works, emphasizing their contemporary value and relevance. It is an invaluable resource for Party members, cadres, and young students to deepen their understanding of Marxist principles, as well as to gain insight into the defects of modern capitalist systems and the advantages of socialist systems.