The invention discloses a knowledge expression model-based complex curved surface digital manufacturing method, and the method comprises the following steps that S1, a knowledge integration module, a simulation module and an in-situ measurement-compensation module are constructed; S2, a similarity threshold alpha is established by adopting a semantic understanding reasoning strategy based on W ND IC; S3, when alpha is more than or equal to 0.95, the knowledge integration module is directly connected with and controls the in-situ measurement-compensation module; S4, when alpha is more than or equal to 0.80 and less than 0.95, the knowledge integration module is connected with and controls the simulation module to modify the defects existing in the model, after the defect modification is finished, the simulation module transmits the model data to the in-situ measurement-compensation module after data conversion, and the in-situ measurement-compensation module carries out numerical control machining; and S5, when alpha is less than 0.8, the cooperation of human experts is required to complete the process; and the knowledge expression model-based complex curved surface digital manufacturing method establishes an integrated knowledge expression model in three fields of through design, processing, simulation optimization and measurement, and based on this, a knowledge base and an inference mechanism are constructed, and the knowledge expression model-based complex curved surface digital manufacturing method provides theoretical and technical support for intelligent closed-loop manufacturing of the complex curved surface part.