In view of the problem that φ50 mm drill pipe is used for standard penetration test(SPT) without correcting the SPT count,the SPT count of φ42 mm and φ50 mm drill pipes in the same site are tested,the hammer energy ratio and the SPT count of the two drill pipes are obtained,and the correction method of φ50 mm drill pipe SPT count through data comparison is established.Taking the first phase of Donggang project in Yantian port area,Shenzhen Port as an example,the SPT count of two types of drill pipe in different soil layers are measured.The results show that the total input energy of φ50 mm drill pipes is about 5% higher than that of φ42 mm drill pipe.According to the relationship between the hammer energy ratio of the two drill pipe types and the ratio of the SPT count,the correction coefficients of the SPT count of silty clay and medium coarse sand are 0.85 and 0.87 respectively when φ50 mm drill pipe is used in this site.