Abstract: In order to solve the problems of incompatibility of evaluation results and the difficulty to reflect the real water quality property of comprehensive evaluation of agricultural irrigation water quality, a new comprehensive evaluation method-projection pursuit model based on the technology of data exploring, which was optimized by the immune genetic algorithm(IGA-PP), was presented to evaluate irrigation water quality. The result shows that, compared with the traditional water quality evaluation methods, the mathematical concept of IGA-PP method is much simpler and clearer. The evaluation results of IGA-PP are more precise and reasonable, which solve the incompatibility and unilateral problem of comprehensive evaluation. IGA-PP has better applicability for forecasting and evaluating agricultural engineering system.