The invention provides an FBAS function model for product conceptual design and a product conceptual design method based on the function model and gene expression, and aims at solving the problems of low structure scheme feasibility, long design period and high cost caused by fuzzy and incomplete design information in traditional conceptual design. The method comprises the following steps: analyzing forward product design process from top to bottom to build a function expansion model on the basis of function, behavior, attribute and structure; then performing analog on biological genes, and proposing a concept, a model and a coding method of a product gene; and then performing the product conceptual design through operations such as product gene crossing, combining, transcription and translation. According to the method, the key information in the conceptual design is defined through the product genes; the genes are crossed and combined to obtain more gene forms corresponding to various function units; the genes are subjected to transcription and translation, thus more design scheme feasible solutions can be obtained, and more selection space is provided to the product creation design, and as a result, the product innovation can be effectively improved.