Abstract： Malignant pleural effusion （MPE） is a common complication of advanced cancer. Western palliative treatments face limitations such as high recurrence rates and obvious adverse reactions. In traditional Chinese medicine （TCM）， MPE is categorized as suspended fluid， and its pathogenesis lies in yang-qi deficiency， dysfunctional qi transformation of triple energizer，and pathological fluid retention. But this interpretations often suffer from fragmented pathomechanism explanations and disjointed therapeutic approaches. Based on the theory of "yang transforms qi，yin shapes form" from the chapter Grand Discussion of Yin-Yang in Response to the Nature and Body in Su Wen （Basic Questions），this study innovatively constructs a "deficiency-stasis-toxin" closed-loop pathomechanism model for MPE. The core of this model lies in yang-qi deficiency leading to dysfunctional qi transformation of triple energizer，causing a pathological reversion of fluids from an immaterial functional state into a substantial pathological yin turbidity. This turbidity further coalesces with blood stasis and cancer toxin to form encysted pathological aggregates. These three pathogens of deficiency，stasis，and toxin engage in a vicious cycle characterized by deficiency begetting stasis， stasis brewing toxin， and toxin damaging deficiency. Accordingly， the fundamental therapeutic principle of warming yang to resolve fluid retention is established. A stratified therapeutic system is further constructed，integrating warming yang to restore qi transformation targeting the root by revitalizing the dynamic source of qi transformation by warming yang qi in the upper，middle，and lower energizer，and resolving fluid and dispersing yin turbidity targeting the branch by employing stage-specific methods to dissipate the substantial yin turbidity based on its pathological progression from formless to formed. These methods include transforming qi and moving water， breaking stasis and dispersing aggregations， and softening hardness and scattering nodules. This integrated system synthesizes classical TCM theory with modern mechanistic understanding，transcending the limitations of traditional therapeutic approaches， and providing a systematic theoretical foundation and practical pathway for the integrated traditional Chinese and western medicine management of MPE.