Abstract: In order to establish CPIII vertical control network in high-speed railway with high efficiency and accuracy, a CPIII trigonometric leveling network method based on difference method was proposed, which was performed simultaneously during establishing the horizontal control network. In this method, a mathematical model of observation equations with weighted values, which are determined according to the error propagation relationship between indirect height difference and direct observations, is built, and the parameter adjustment method is used to obtain the accurate elevation values of CPIII control points. Then, a computing software based on the proposed algorithm was developed and tested in real application. The test result shows that the derived height from the proposed method, compared with the leveling height at the same point, has a confidence level of 99.40% for tolerance interval of -3 to 3 mm. Therefore, using the CPIII trigonometric leveling network obtained by the proposed method to replace the CPIII leveling network can meet the accuracy requirement of CPIII vertical control network.