The methods of analytic hierarchy process (AHP) and cause and effect diagram were linked to analyze the quality of air conditioning installation.Cause and effect diagram was used to spot the influencing factors on the quality of air conditioning installation.Then,judgment matrix of AHP was used to judge the comparative importance of each influencing factor in every hierarchy,through introducing the judgment scale that can reflect most people’s judgment and using approximate calculation method to calculate the largest eigenvalues λmax and weight number of corresponding factors ranking.Finally,the top three key factors for quality control of air conditioning installation were found out through prioritizing.