The invention discloses a simulation test device for debris flow and a test method and belongs to the field of debris flow simulation test, in order to solve the problem that the present simulation test device for debris flow cannot continuously experiment. The simulation test device for debris flow comprises a charging basket, a runner, a lifting system and a stirring system, wherein the stirring system is arranged at the top of the charging basket; the device further comprises a control panel, a hydraulic system and a lateral baffle; a turbine pump is arranged on the middle part of an inner wall of the charging basket; the hydraulic system comprises a hydraulic cylinder and a hydraulic jack set; the runner is formed by connecting an inclined chute, a semicircular arc slot and a horizontal chute; the hydraulic jack set is supported under the inclined chute; the bottom of an extension pipe is supported by the hydraulic cylinder. According to the invention, the inclined chute is supported by the hydraulic jack; the combination of the arc chute and the inclined chute can realize the adjustment for the gradient of the inclined chute; the debris flow effects at different gradients can be simulated.