Abstract: In engineering practice, non-standard cross section was widely used to optimize the hydraulic conditions of horseshoe tunnel section, but the complex geometric shape may lead to complicated hydraulic calculation. In order to solve this problem, the analytic formula of hydraulic elements corresponding to any water depth and two kinds of non-standard horseshoe-shaped sections were deduced by means of geometric segmentation and integral method. According to the derivation result, the exact analytical solution can be obtained conveniently and quickly by using the software such as Excel. Then, based on the water diversion project in central Yunnan Province, the derivation formula was applied to the hydraulic elements formulation of non-standard horseshoe tunnel section, and the results were accurate and reliable, which could provide reference for hydraulic calculation of similar projects.