In the process of modern industrial production, the request of the air-condition is very strict. On the one hand, it directly influences the quality of industrial products, On the other hand, in the energy nervous today, saving energy and reducing consumption of air conditioning system also put forward higher request. This paper puts forward a method based on the least warn control algorithm, first, On multivariable systems structure identification and parameter estimation through recursive least squares method. Meanwhile, According to the characteristics of coupling about multivariable systems, decouple, finally, minimum alert control on this system, and realize simulation on MATLAB.