The main cable is the main load-bearing member of suspension bridge, and the correctness or otherwise of the main cable alignment is the key to the success or failure of suspension bridge construction. Therefore, the calculation methods and results of main cable profile are very important in the design and construction of large-span suspension bridges. This paper briefly introduces two approximate calculation methods of the line shape, and at the same time focuses on a very close to the actual line shape of the main cable of the precise calculation method, and lists the results of the calculation of Yichang Bridge with this line shape calculation method.