In this paper, per capita area is used to describe service level. An AnyLogic simulation system is formulated to study on subway design parameters, which influence the service level of transfer stations. For stations in the case, it is suggested that the platform width in different transfer stations should be different. According to the simulation, the platform width of “One”, “Cross” and “T” type transfer stations should be widened by 3.6m, 1.2m and 2.4m respectively on the basis of the original models. As a result, the service level of the platform at the most crowded moment can be upgraded from B to A, and the increase of the minimum per capita area of the platform is 34.9%, 15.8% and 21.2%. Besides, the width of stair should be widened by 0.4m, 0.8m and 0.2m, so that the service level of the platform can reach the peak, and the average per capita area of the platform can reach 1.754 m2/p (square meter per person), 2.000 m2/p, 2.178 m2/p. Finally, if conditions permit, the stairs should be placed at both ends of the platform.