The invention relates to a solid-liquid multiphase dynamic numerical simulation method suitable for debris flow, which adopts a numerical simulation model of a solid-liquid multiphase debris flow power process, and comprises the following steps: firstly, acquiring debris flow channel starting, movement and accumulation dynamic information through field scientific investigation and physical and mechanical experiments; Determining high-precision topographic data and object source data in the calculation area through a geographic information system or a high-precision 3D topographic scanner, expressing the high-precision topographic data and the object source data as (x, y, h) grid data through grid coordinate conversion, and respectively representing x, y and h as x, y coordinates and elevation values h of topographic points; Soil and fluid parameters are determined and estimated from a proper amount of soil samples in the channels in the calculation area through indoor physical and mechanical experiments, so that all parameters needing to be prepared in the pretreatment stage of the numerical method are obtained; According to the method, the scientificity and reliability of numerical simulation research in the debris flow dynamic process are improved, the pertinence of disaster prevention and control is improved, the prevention effect is enhanced, and technical support is provided for debris flow disaster reduction.