This paper focuses on investigating, identifying, and systematizing the lexical-grammatical means used to express modality through the structure of compound sentences in the works of writer Nam Cao. By analyzing a representative corpus of data from Nam Cao’s literary works, the paper demonstrates the diversity of modality-bearing compound sentence types, including conditional-consequential relations (nếu... thì, hễ... thì, giá... thì), causal-consequential relations (vì/bởi vì... nên, sở dĩ... là vì), additive-progressive relations (càng... càng, đã... lại còn), as well as supplementary, comparative, contrastive, and sequential relations. The results indicate that modal means in compound sentences not only serve grammatical linking functions but also act as sharp artistic tools, enabling Nam Cao to deeply portray the inner world of his characters and express a lucid, philosophical realistic perspective, alongside profound compassion for the destitute lives in the old society.