Abstract: On the basis of elasto-plastic mechanics,similarity theory and rock mechanics,the effect of stress rela-xation groove on the outburst of coal and gas in coal tunnel is discussed in this paper.The analogue experiment hasbeen made in laboratory. The state of stress distribution around coal body can be obtained when stress relaxationgroove of coal tunnel has been developed. The research work shows that the condition of outburst prevention instress relaxation groove of coal tunnel depends on the size of stress relaxation zone.