Industrial wastewater discharge is an important factor causing heavy metal element Cd pollution in water systems. Improper discharge may cause serious environmental pollution. Long-term consumption of crops or aquatic organisms in Cd-contaminated environments will cause various diseases and cause serious harm to the body. Therefore, timely detection of the heavy metal element Cd content is very important for treating and discharging industrial wastewater. Compared with traditional detection methods, energy-dispersive X-ray fluorescence (EDXRF) analysis has the advantages of fast speed, no damage to samples, simple operation, and small instrument size. It is more suitable for application in industrial wastewater treatment sites to detect heavy metal elements in industrial wastewater rapidly. Detection provides a basis for the treatment of industrial wastewater. This article conducts research on factors affecting the on-site rapid detection of Cd element content in industrial wastewater using the EDXRF method. The detection object is untreated flowing industrial wastewater. In order not to affect the process flow, the wastewater sample will flow through a section of the processingpipeline, and the EDXRF detection device will be installed. Outside the processing pipeline, this paper deduces the mathematical model of X-ray fluorescence analysis when the pipeline is square and the X-ray source and detector are vertically located on two adjacent planes of the square pipeline. The simulation analyzes different pipeline geometric parameters and “source-sample” - Explore the influence of the geometric position of the element to be measured on the characteristic X-ray irradiation rate of Cd, verify the accuracy of the theoretical analysis through Monte Carlo method simulation, and obtain the optimal excitation-detection device and its optimized parameters for the square pipe sample. This article conducts MATLAB simulation research based on the established mathematical model. The industrial wastewater solution is set to have a Cd element concentration of 100 000 μg·mL^-1, the medium is an HNO₃ solution with a concentration of 1.09 mol·L^-1, and the incident light ray energy is set to 40 keV, which is brought into parameter calculation, the effects of pipe wall material, pipe wall thickness, detector height, and horizontal distance of the X-ray source on the changing trend of the characteristic X-ray intensity of the element Cd in the standard sample were obtained. At the same time, a Monte Carlo model was established to simulate and study the source outlet ofthe sample. The simulation study was conducted to investigate the influence of the horizontal distance from the source outlet to the sample side, collimator diameter, “source-sample” distance, “sample-detector” distance, detector height, pipe wall thickness, and pipe wall material on the net peak area and peak-to-background ratio of the Cd characteristic peak in the sample. It is found that the pipe wall thickness should be as thin as possible under allowable process conditions, and the commonly used pipe material is better to be polypropylene acid ester plastic. The “sample-detector” distance is 1 mm. The “source-sample” distance and detector height should be as small as possible under objective conditions, such as the device's geometric size and the device's fixing conditions. When the horizontal distance from the source outlet to the sample size is 2.8 mm and the collimator diameter is 2 mm, the peak-to-background ratio and net peak area of the Cd characteristic peak will reach an optimal value.