Economic analysis is made on the mechanized construction of long railway tunnels. The mechanical matching for the construction of long railway tunnels in different rock mass is summarized, and the economic indexes and costs of the construction of long railway tunnels are worked out. Compared with conventional mechanical matching, the mechanized construction can improve the construction progress, shorten the construction period, improve the construction environment, guarantee the construction quality and reduce the construction risks. The mechanized construction has great comprehensive significance, although its direct cost is slightly higher. 