Abstract: In the process of product design, most input information necessary for quality function deployment (QFD) usually possesses the fuzzy and linguistic characteristics. So, various input information of house of quality (HOQ) are regarded as linguistic variable to compile a glossary of fuzzy terms for various linguistic variables and form the fuzzy numbers corresponding to them, with the conventional HOQ theory extended to fuzzy domain on the principle of fuzzy expansion. Elaborates the modeling process of fuzzy information by such theories as four arithmetic operations, fuzzy decision and fuzzy reasoning, which is of theoretical significance to the decisionmaking of products' design in fuzzy circumstances.