利用两群中子扩散方程的解析解，导出快、热中子通量之间的关系，去掉快群与热群方程之间的耦合，将原来的解两群方程的问题，理论上严格地转化成解单独的快群方程问题。快群方程用格林函数节块法进行求解。依照上述理论，研制了三维节块法程序ＮＧＭＤ。对一系列轻水堆基准问题的验算表明，ＮＧＭＤ的计算精度与知名的格林函数节块法程序ＮＧＦＭ相当，而计算时间约是ＮＧＦＭ的１３。 The analytical solution of two neutron diffusion equations is used to derive the relationship between fast and thermal neutron fluxes. The coupling between fast and hot group equations is removed. The original problem of solving two-group equations is theoretically strictly Converted into solitary fast group equation problem. Fast group equations are solved by Green’s function nodal method. According to the above theory, a three-dimensional nodule method NGMD was developed. An examination of a series of LWR benchmark problems shows that the computational accuracy of NGMD is comparable to that of the well-known Green’s function NBCM, and the calculation time is about 13% of the NGFM.