Abstract: To mitigate the impact of positive ions and metal splatters on the signal-to-noise ratio and lifespan of the electron reflected detector during electron beam welding, a quadrupole high signal-to-noise ratio electron reflected detector with a reflecting surface was designed using the Monte Carlo method and Multiphysics Simulation software. The entire process of signal reception by the detector was simulated, and the influence of its structural parameters on the collection efficiency of reflected electron signals was investigated. The simulation results show that, under an accelerating voltage of 60 kV and a working distance of 200 mm, the detector achieves the optimal collection efficiency of 2.73% when the reflecting surface tilt angle is 165° and the collection surface tilt angle is 105°. When the reflecting surface tilt angle (α) and collection surface tilt angle (β) are fixed, the collection efficiency decreases with an increase in the working distance (h). Experimental results verify the simulation findings, and a comparison with metal plate detectors' imaging results shows that this reflected electron detector improves the image contrast by 38.8%. The reflected electron detector can also clearly identify tungsten mesh samples with a wire diameter of 100 μm.