Abstract: This paper analyzes the semantic feature modeling of new generation，consults research results of Bidarra etc，uses vali-
dity criterion，and establishes methods of feature conversion to semantic feature modeling.Based on the mathematical methods，this paper addresses the problem how to convert the design feature representation into machining feature representation in a mathematical model.Design features in the design domain are represented by a set of faces of each feature geometry and a set of attributes such as dimensions and material feature.Machining features in the manufacturing domain are represented by a number of faces and relationships between these faces that are meaningful for the process operations.Using a mathematical description of the feature mapping process，machining features can be deduced and formed by the set operation，and the difficult problem of feature interaction can be described mathematically and converted in theory，thus to make product model editing easier.