Provided is a method for discriminating sand-gravel stratum liquefaction through a standard penetration test. The method comprises the steps that a test sand-gravel stratum is drilled 5cm above the elevation of the test sand-gravel stratum; a standard penetration test device is connected and an injection device is put to the bottom of a drill hole after a connector of a feeler lever is inspected; then the injection device is driven into a saturated sand-gravel stratum by 5cm through a pilereing hammer, the standard penetration hammering number starts to be recorded for every 3cm of driving, and the total test range is 30cm and is divided into 10 test sections; a relation curve graph between the hammering number of each test section and the corresponding penetration degree is drawn, the invalid test sections affected by sand gravel of large grain sizes are removed according to the relation curve graph, and the standard penetration hammering number of 30cm of penetration is equivalently converted according to the standard penetration hammering number and the penetration degree of the valid test sections; and seismic liquefaction discrimination of saturated sand gravel is conducted according to the standard penetrate hammering number equivalent to 30cm of penetration into the saturated sand gravel. By adoption of the method for discriminating sand-gravel stratum liquefaction, the defect that in the prior art, the standard penetration hammering number tends to be large due to the effect of the sand gravels of the large grain sizes, and the seismic liquefaction discrimination result tends to unsafe accordingly is overcome.