Aiming at liquefaction of saturated fine sand in meizoseismal area and taking the Puqian Bridge project as the test site, this study simulated the vibration response of the free field under seismic action by the vibration table model test and the laminated shear model box. The variation law of pore pressure ratio of saturated fine sand at different depths under ground vibration intensity of 0.15g~0.80g (g represents gravity acceleration) was analyzed, and the liquefaction discrimination method of saturated fine sand was discussed. Results show that the growth of ultra-quiet pore water pressure and pore pressure ratio of saturated fine sand lagged behind ground motion stress, and the deeper the sand was, the longer the lag time. The saturated fine sand with a depth of 5 cm, 60 cm, and 110 cm was liquefied when the local vibration intensity was greater than or equal to 0.15g, 0.20g, and 0.25g respectively, and the pore pressure ratio stability value was greater than or equal to 0.8, which was proposed as a critical pore pressure ratio of saturated fine sand liquefaction. The liquefaction determination results of the existing common methods were discussed and a new method for discriminating the liquefaction of saturated fine sand by the criterion of saturated fine sand depth, ground motion intensity, and pore pressure ratio was proposed. It provides technical reference for similar projects and scientific basis for rational design and construction of bridge foundation before paving.