According to the body comfortable which has the feature of unabsolute and fuzzy in the indoor thermal environment, we study and produce a kind of Multi-variables fuzzy comfortable evaluate instrument. The instrument takes the temperature, relative humidity, flow rate of the indoor air as the input variables, and takes the fuzzy synthetic evaluate methods as the principles, and takes the ADμC812 single-chip operator as the core of the hardware circuit. It gives out the coefficient of the affecting factors and the classification of the lingual value of the linguistic variables. As to the problem of the affecting factors such as temperature and relative humidity which have the interaction relations, it can solve it by adopting different coefficient and the demarcating of the lingual value. It can achieve the functions of data collecting, calculation synthesis, interaction relations loosening and getting the evaluate results. By actual testing it has high credibility and is an efficient tool to evaluate the comfortable of indoor thermal environment and can be widely applied.