Abstract: The Linjiang Avenue tunnel in Guangzhou financial city is constructed by open excavation method, and the tunnel foundation pit needs to cross the tangxiayong River horizontally. Tangxiachong is located in the tidal zone of the Pearl River, and the water level shows a large periodic change under the influence of tide. In order to improve the efficiency of tunnel construction and make scientific and rational use of construction resources, this paper takes the open cut tunnel construction as the research object, and studies the river diversion technology under the influence of the tidal effect of the Pearl River. Based on the comprehensive analysis of the location relationship between the tunnel and the river and the structural characteristics of the tunnel, the scheme of the diversion channel crossing the tunnel structure is proposed, and the corresponding measures for the tidal effect are formulated. The technology has been applied in the construction project of Linjiang Avenue tunnel in Guangzhou financial city. The diversion open channel meets the flood control requirements for a 20-year return period and can operate safely in an environment where the periodic drop of water level exceeds 2.3 meters. The engineering practice has proved that the diversion scheme is feasible. Compared with the traditional diversion scheme, the completion time of the tunnel structure is more than one month ahead of schedule. The tunnel foundation pit structure and groundwater level remain stable during the construction process, which can provide reference for the construction of similar projects.