The invention belongs to techniques of building structure design, and in particular relates to an anti-shearing construction method of an underground reinforced concrete trench with water pressure at a turning part. The method is characterized in that a reinforced concrete shear key is arranged below the outer side trench wall of a common reinforced concrete trench at the turning part, wherein the reinforced concrete shear key and the trench wall are poured integrally, and a shearing effect which is generated on the outer side trench wall of the trench by the water pressure effect in the trench at the turning part is resisted through the reinforced concrete shear key. The anti-shearing construction method provided by the invention has a wide application range, is not restricted by the excavation range of a foundation pit of the trench or other conditions, can be put into use under common construction site conditions, can facilitate construction, and is good in economical efficiency.