As the key process of restricting time limit for Liaofang irrigation area phase II project，arch rib concrete pouring construction of large span aqueduct is of great difficulty.Through comparing construction schemes，arch rib concrete adopts 3 times 7 blocks and crossbar symmetric pouring technology，which is to innovate the construction ways of arch rib in large span aqueduct.This technology can reduce the concrete temperature stress in the arch rib concrete pouring process and the template deformation which caused by concrete load，ensure the concentric roundness of arch rib meeting the design requirements and construction quality of arch aqueduct.It has wide application prospects.