Background <p>Pulsed slow positron beam with high timing resolution is essential for detecting microscopic defects. The reflective chopper, which determines the quality of the initial pulsed beam, is fundamental to achieving high timing resolution.</p> Purpose <p>This study analyzes the electrode characteristic of the chopper to examine its influence on energy distribution and establishes the relationship between its structure and energy distribution. The correlation between the chopper’s capacitance and the time response of the pulse signal is investigated, and the method of reducing the capacitance of chopper is proposed. This paper presents the development direction for generating a high-quality pulsed beam using a chopper.</p> Results <p>Based on the simulated results, a chopper with mesh number of 100, spacing of 8 mm and capacitance of 5 pF was designed, demonstrating the successful realization of a 0.75 ns sub-nanosecond chopping pulse beam in the laboratory.</p> Conclusion <p>This research not only guides the design of the chopper for a beam with high-energy distribution but also enhances the quality of the pulsed beam. Moreover, it is of significant importance not only for the pulsing of positron, but also for other microscopic particles.</p>