The construction risk of deep metro foundation pit in waterrich composite strata is high, and there is little relevant research. Hence, the characteristics and risk of excavation of deep metro foundation pit in waterrich composite strata are summarized based on risk source analysis and construction experience of Guangzhou Metro; and the construction method of "excavation and assessment, presealing, defect repairing, scientific dewatering, uniform and adequate backfilling, accurate measurement, timely support and rapid construction" is proposed and introduced. The abovementioned method emphasizes the integrality and waterproofing capacity of the retaining structure, richwater risk and successful completion of highrisky construction procedure. The method takes the risk assessment as the basis and the countermeasure preposition as the core, by doing which the risk of deep foundation pit construction in waterrich composite strata can be effectively controlled.