The article explores swirling abrasive water jet from angles of nozzle wear mechanism and drilling. By theoretical analysis, this paper proposes that the decisive factors in the wear of swirling abrasive water jet nozzle are abrasive wear and erosion wear. Abrasive wear is the main reason for the wear of nozzle inner wall, while erosion wear plays the key role in the wear of nozzle entrance. These two wear mechanisms are studied in detail in this paper by using the finite element analysis to simulate the stress state of the nozzle. The result of the simulation shows that the maximum stress lies in the place where the cone sect meets the straight sect, stress in the cone sect is relatively small and grows gradually, the average stress in the straight sect is larger than that of the cone sect,and the stress at the entrance is quite big. Comparison between the stress of swirling and common jet nozzle tells that the former maximum stress is far larger that the latter. It can explain that the wear of swirling jet nozzle is more severe than common jet nozzle. The way how various parameters effect the wear of the nozzle is carefully studied in the article. These parameters include abrasive particle characteristics(abrasive particle shape, abrasive particle diameter, abrasive particle hardness, abrasive particle concentration), material hardness and quality of nozzle(nozzle material hardness, ratio of particle hardness to nozzle hardness, nozzle quality), nozzle structural shapes(entrance angle, nozzle hole diameter), working parameters( pressure and flow rate),etc. The result indicates the change of these parameters can not only make jet structure change,but also effect the wear rate of the nozzle. In order to analyze drilling performance, a series of experiment are carried out to study the influence of the parameters. For example, pressure,distance,nozzle hole diameter, line-number of swirling object, screw-pitch of swirling object and central hole of swirling object. The result shows that the section of swirling abrasive water Jet nozzle is loop, the shape of the aperture is roughly column the middle of which has an inner cone, and the shape and the radius of the loop and aperture varies with the working and structure parameters. This result is consistent with the theoretical analysis.