Line and slope adjustment is the last process of rail transit line design, through the design of slope adjustment to fully solve the problem of boundary incursions caused by construction deviations, thus ensuring the safe and good operation of trains in the future. The traditional method of line and slope adjustment relies on the experience of designers, which is a large amount of work and the design accuracy is not high enough. In this paper, the optimisation model of line and slope adjustment is constructed based on Grasshopper, which is currently focused on optimisation of the planar line position, and solved by genetic algorithm and simulated annealing algorithm. The above method is applied to a real rail transit shunting case, and the machine-selected scheme is better than the manual scheme, which verifies the validity of this paper’s method.