Abstract: In order to study the predication of hydraulic gradient for coarse sand slurry in the horizontal pipe， based on the analysis and calculation of the coarse sand particle′s balance relationship in the horizontal pipe， by adopting a research method of adding a correction factor L before interference force is put forward， and by using related experts′ experimental data and through data fitting， an expression of correction coefficient L is given out. Based on this， by using an efficient resistant model， a hydraulic gradient calculation model for coarse sand slurry in the horizontal pipe is developed. The calculation model is verified by related experts′ experimental data and it is found out that the deviation between the calculated values by author′s model and the measured values is not more than 10%， and that after considering the correction factor L， the model-calculated values will relatively increase and move closer to the measured values. So in the coarse sand slurry pipeline， the interference force acting on coarse particles needs to be revised by correction factor， thus the hydraulic gradient calculation model put forward for coarse sand slurry can give a certain reference to the study of the transport of coarse sand slurry in pipes.