The evolution of pressure arch of underground engineering excavated in different ways was analyzed.The results of analysis showed that with progress of excavation the space between two the inner borders of pressure arch on the top of underground engineering changed little,but the thickness of the pressure arch was increasing;the space between two the inner borders of pressure arch was larger in the middle of the floor and the two sides of underground cavern engineering than other part;core-soil had a greater effect on the space between two the inner borders of pressure arch on the base of underground cavern engineering;step-by-step excavation could make the space between two the inner borders of pressure arch reduce,but had a little impact on the thickness of pressure arch,that is,could make the pressure arch closer to the edge of underground cavern engineering.