Aiming at the heavy metal cadmium pollution accident in the Beijiang River Basin in December 2005, a one-dimensional river heavy metal migration and transformation model was established, and the parameters of the model were determined and verified by combining the measured data of the pollution accident. From the calculation results, when the cadmium concentration value in the water body is large, the calculated value of the heavy metal model fits well with the measured value, while when the cadmium concentration value is low, the fitting effect is not ideal, in addition, the cadmium concentration in the water body decreases from upstream to downstream with the movement of the water flow, which indicates that the heavy metal is gradually deposited in the bottom mud under the action of adsorption and sedimentation.