Abstract: The standard penetration test and liquefaction index analysis were carried out on a section of sandy soil in the old course of the Yellow River area, and the liquefaction potential of sandy soil under different compactness was analyzed and compared by using dynamic three-axis indoor test. The results show that most of the old course of the Yellow River area and surrounding areas are liquefied strata, and the geomorphological units are impacted ridges. According to the change of small deformation and pore water pressure in dynamic three-axis test, the liquefaction process can be divided into three stages: initial change stage, mid-term stability stage and final acceleration stage, and the liquefaction internal mechanism corresponds to each stage. The compactness is positively related to the anti-liquefaction of sand soil, and the amplitude of small deformation and pore water pressure is affected by the dynamic triaxial test. Through the liquefaction test comparison and the supplementary test, it is found that the dynamic triaxial test has a narrower liquefaction boundary and the liquefaction standard is more strict than the standard penetration test.