The hydraulic transport of coarse and gravel sand has its characteristics and the adaptability of the existing hydraulic calculation model for calculating the hydraulic loss and criticality of this type of soil needs further inspection.In response to the problem of large transmission resistance and high risk of pipe blocking in the Malaysian Johor Bahru Garden Filling Project of China,we carry out the hydraulic transport characteristic test using the newly built large-scale and two-phase flow transport test platform,and test the hydraulic loss in the case of different flow rates and concentration,and the movement pattern of sand in the pipeline is observed by means of high-speed photography.Through the statistics and fitting analysis of the test data,the characteristics of hydraulic transport resistance,critical flow velocity and average slip rate are studied.A hydraulic resistance and critical flow velocity calculation model for the soil is proposed,and the model is used in actual engineering projects.