There are a lot of uncertainties in the establishment of traditional normative methods，so a comprehensive research method is urgently needed to discuss the liquefaction discrimination in complex sites. Based on the emergency repair project of the immersed pipe in Baotou section in Shanghai，this paper first adopts the standard penetration test method (SPT) to qualitatively evaluate the sandy silt soil within 20 meters of the research area. Using the absolute difference percentage method (APD) proposed in this paper，35 groups of soil samples with accurate discriminant results and 14 groups with discriminant errors are divided. Secondly，referring to the theoretical thought of discriminant analysis and the theoretical thought of discriminant analysis， the physical and mechanical parameters such as average particle size D50, heterogeneous coefficient Cu，specific penetration resistance Ps，standard penetration point depth ds，groundwater burial depth dw and standard penetration hammer number N63.5 are added to the liquefaction evaluation. Using the soil samples with accurate discriminant results，a distance discriminant analysis model (DDA) suitable for the engineering geological characteristics of the research area is established to quantitatively evaluate the soil layers with discriminant errors or errors. Finally，choose the discriminant results based on the results of the "advantage combination". The research results show that the established comprehensive evaluation system for sand liquefaction is highly pertinent and adaptable to the research area. It is established that 37 groups of the 49 groups of sand and soil layers in the research area are liquefied. Through reasonable anti-liquefaction and subsidence measures，the steady progress of subsequent projects are guaranteed，which is stable for sand liquefaction in fields with similar geological conditions. The evaluation provides reference and reference.