Aim at the deficiency of product conceptual design solving presently, a conceptual design process model was established based on the theory of axiomatic design, and a formalized description of product conceptual space was proposed. The description of product concept space combined with BOM was finished firstly. Subsequently, the plan appraisal method based on axiomatic design was designed. Finally, a case was given to validate that the model could efficiently make up for the disadvantage of information axiom during plan decision-making process. The results indicated that the description of product concept space was optimized by the appraisal method, and the product conceptual design solving efficiency was improved. 