Material selection in mechanical products based on total life cycle design is a complicated work, which should be studied systematically. A material selection model of mechanical products based on total life cycle design was proposed. A set of candidate materials were screened out, and then assessed according to the technical, economic and environmental assessment index. The candidate materials were ranked by using by using Z-transformation method in each of the assessment index. Different weights were assigned to each of the three assessment indexes, and global assessment was carried out according to different strategies or requirements which pay more attention to technical, economic or environmental performance of the material product used. A case in selecting aircraft structure element material was studied. The analysis results showed that the method could rank the candidate materials and selected out the “optimized material”, and the influence of the subjectivity of designer was reduced. The method provides some practical values for preliminary material selection in the early design stage of the mechanical products based on life cycle design.