Abstract: Simulation experiments of coal and gas delay outburst in rock cross-cut coal uncovering were done under the condition of fixed vertical stress or horizontal stress with a large-scale test device for simulating the coal and gas outburst and the outburst port closed by a mixing-material of coal powder and gypsum-simulated hard coal. The results show that the relationship of critical gas pressure and horizontal stress at delay outburst is exponential and reversely changes under fixed vertical stress, but relationship of critical gas pressure and vertical stress at delay outburst is a quadratic polynomial and reversely changes under fixed horizontal stress. The intensity of outburst reflects the degree of damage at delay outburst. It is a positive correlation with critical gas pressure and a negative correlation with ground stress.