Abstract: Based on ANN model and reliability theory the limit state function of liquefaction and the probability function of liquefaction are established. In terms of the reference value of SPT in China code a simplified probabilistic procedure for liquefaction evaluation is proposed. The assessment of soil liquefaction potential is based on the liquefied reference value of SPT which is the liquefaction critical value of SPT for given ground acceleration, the depth of soil layers and ground water levels, and is also related to earthquake magnitude and liquefaction probability. The two corrections factors for earthquake magnitudes, and the depth of soil layers and ground water levels, are respectively given for estimating liquefaction potential at any soil layer and various earthquake magnitudes. In addition, based on the procedure another liquefaction criterion according to the design earthquake groups is also given to be convenient to engineering practice in China.