Taking three-dimensional design of channels in the water conservancy and hydropower industry as the object of study based on secondary development technology of CATIA, the theory and engineering practice of three-dimensional design of water conservancy and hydropower were consideted to develop a practical application program of three-dimensional design of channels with high-degree automation by Combining CAA development technology with CATIA software. This application is expected to solve channel design problems in the water conservancy and hyclropower industry, and the results of its development have been applied to the three-dimensional design of the channels in South-to-north Water Diveision Project. The practice of channel design shows that this method can reduce the workload, shorten the cycle, and reduce the difficulty of channel engineering design. It can save time and human resource cost for water conservancy and hydropower design organizations with ensured quality and quantity, as well as provide a reference for secondary development of other industries.