介绍了2.5维自主研制的并行电磁粒子模拟程序NEPTUNE2D初步研发情况。该程序基于JASMIN并行自适应结构网格支撑框架研制，并行效能高，可扩展性强，且支持动态负载平衡；采用新型PIC算法替代传统算法，避免求解泊松方程修正电场，更适用于大规模并行计算；程序支持r-z坐标系下的器件仿真，可应用于高功率微波器件、电真空器件的快速模拟设计。该程序现已完成电磁场更新、粒子推进、电磁场注入/引出、粒子发射/吸收等基本物理功能模块的研制，并通过同轴线、圆波导、同轴二极管及无箔二极管算例模拟验证了模块的正确性。最后，应用NEPTUNE2D程序设计了一个高效同轴相对论返波管，给出了粒子模拟结果和并行性能测试结果。

The development on a parallel 2.5D electromagnetic and particle-in-cell code named NEPTUNE2D is introduced preliminarily. The code is developed on the J parallel adaptive structured mesh applications infrastructure (JASMIN), with high parallel efficiency, strong expansibility and adaptive load-balance. A new PIC method is used instead of the classical one, which is more suitable for massively parallel simulation. This code can construct and simulate devices in the R-Z coordinate, and it is capable of fast simulation and design of high power microwave (HPM) devices and electron-vacuum tubes. At present, basic physical function modules are accomplished, such as electromagnetic field update, particle movement, electromagnetic wave input/output and particle injection/absorption. This code is verified and validated by simulations of a coaxial-line, a cylindrical waveguide, a coaxial diode and a foilless diode. Finally, by using this code, a CRBWO (coaxial relativistic backward wave oscillator) with high efficiency is designed and simulated. The physical figures are presented and parallel efficiency is given.