Abstract: Laser method and comprehensive method (pipette method-sieve method) are commonly used to test the sediment grain size characteristics. Due to the differences in testing principles and analysis processes, the test results obtained by these two methods for the same sample are often not completely consistent. In order to explore the commonalities, differences, and correlations between the two methods, and establish a conversion relationship between the results by laser method and comprehensive method suitable for this sea, the authors in this research compared testing results by these two methods from 49 sediment samples in Caofeidian. The results show that: ① Sand content measured by laser method and comprehensive method is roughly equal. And silt content measured by laser method is generally higher than the result by comprehensive method, and the clay content measured by laser method is generally lower than the result by comprehensive method. ② The difference between laser method and pipette method mainly occurs at 10φ, and the clay content by comprehensive method significantly increased. The difference between laser method and sieve analysis method mainly occurred in the coarse end grain, and the coarse end grain content is generally higher measured by laser method. ③ The correlation between laser method and comprehensive method in grain size parameter regression analysis gradually decreases as the grain size decreases. The slope and intercept of the gran size parameter regression equation also do not have a unified conversion relationship with previous research results. It is found that laser method is feasible in measuring the grain size characteristics of sediments, and a data conversion model was established between laser method and comprehensive method in Caofeidian. The data results obtained by these two methods can be converted to each other with a grain size range of -1, 4φ. The difference of grain size characteristics by laser method and comprehensive method is clarified, which can be used as a reference for the measurement of grain size characteristics of sediments and a improvement of testing methods and procedures.