To address the challenges of numerous uncertain factors, difficult-to-quantify risk assessment, and excessive subjectivity in deep foundation pit project risk assessment, we propose a risk quantification assessment method that combines CRITIC and grey system theory, leveraging the deep foundation pit project of Daishan Station on the Nanchang Rail Transit Line 3. We establish a risk assessment index system for the construction period of subway deep foundation pit project. We use the CRITIC method to calculate the objective weights for each metric and, in combination with the theory of grey systems, to determine the safety risk level and risk value of subway deep foundation pit construction. The results show that the proposed method is able to scientifically and reliably assess the risk level of deep basins, reducing the influence of expert subjective factors and taking into account the interrelation of the indicators. It can reasonably reflect the level of risk in deep foundation pit construction and is suitable for foundation pit engineering where there are numerous risk factors and ambiguities. It can provide a decision basis for risk management of similar deep-basin pit projects.