Based on the principle of variable fuzzy set, the quality evaluation system of drip irrigation maize underfilm was established. According to the experimental data from 2015 to 2018 of Xiangyang Village, Tongyu County,the quality evaluation index system of "one target, three layers and 20 indicators" was constructed. Using Delphi programming language, the system was proved to be efficient and accurate by means of extreme value method and case method. The quality evaluation of drip irrigation under maize film was a complicated multi-index and multi-level fuzzy evaluation problem. The principle of variable fuzzy set was one of the methods to evaluate the quality of drip irrigation maize under film. The reliability of evaluation results could be improved by changing parameters and establishing different hierarchical eigenvalue calculation models. On the basis of introducing the principle of variable fuzzy model, the quality grade of drip irrigation maize under film in western Jilin Province was evaluated in the paper, and the results showed that the quality level in 4 years was above "medium", among which, the quality level reached "good" in last two years, and the evaluation results showed an upward trend year by year. The evaluation results were in line with the actual situation, which proved that the evaluation system was reliable, convenient and adaptable, which filled the blank in the quality evaluation system of drip irrigation under maize film.