Abstract: Jet singlet oxygen generator is the most stable energy generating device for the chemical oxygen iodine laser. The three dimensional simulation of the jet chemical oxygen iodine laser is presented, which shows the structure of flow field in the reactor and the distribution of the components. It is pointed out that arrangement of liquid jets influences the operation of jet singlet oxygen generator under the same specific surface area. Moreover, the jet singlet oxygen generator with two gas entrances has a lower flow channel resistance compared to that with single gas entrance under the condition of the same flow. These results are meaningful for further optimization of jet singlet oxygen generator.