Abstract: Selection of well completion system is influenced by many factors. Nowadays, it is mainly quantitatively determinedby reservoir properties, downhole operation and requirements of petroleum engineering. It is necessary to give the quantified targetsand model. In this paper, a model of well completion system optimum selection which is comprehensively evaluated based on catastrophetheory was developed. Firstly, a global evaluation system is established including technical description, executive instruction andeconomic target. Then, 10 sub-indications are quantified and normalized. At last, all well completion ways are evaluated and selectedaccording to their values. This method averts the risk of deciding weight subjectively in the fuzzy rating and analytical hierarchy process.Its weights are given by their intrinsic mechanism in normalization. Therefore, the model has less subjectivity and more practical appraisaland faster computation speed. Field practice shows the model is of guide use for well completion system selection.