In order to study the effect of water jet arrangement on conical cutter cutting performance, rock broken mechanisms under the three arrangement modes(no water jet mode, water jet praevia mode and water jet lateral mode) were analyzed based on Evans theory, and mathematical model of the hole compressive stress was obtained. According to the model, water jet praevia mode can reduce the conical cutter cutting force more obviously than water jet lateral mode, and the correctness of above mentioned research results were confirmed in cutting test. The cutting test also showed that: in the condition of this paper, water jet praevia mode could reduce 37.52% cutting force and increase 6.9% fractal dimension of the broken rock compared to no water jet mode; water jet lateral mode could reduce 24.36% cutting force and increase 4.6% fractal dimension of the broken rock compared to no water jet mode, but this combination mode had obvious effect on improving proportion of big lump detritus.