Research conclusions: The module was successfully applied in upgrading of the Chengdu － Chongqing railway． The application showed the module interface was friendly and its performance was stable． It could automatically search the scope of the closure mouth，calculate the plane and vertical data of the closure mouth according to the given track space，detect the plane data that got out of line，gave alarm for the mistaken information with tracing indication to the mistaken area，and rapidly and accurately draw the plane and cross － section drawings． It could provide a audio － visual platform for the designer to check the design rationality of the closure mouth to improve the design quality．