Abstract: A novel 3D non-splitted field finte-difference time-domain(FDTD) absorbing boundary condition (ABC) called the nearly perfectly matched layer(NPML) ABC is proposed. In the rectangular coordinate system, the variables of partial derivatives for space are directly stretched in the Maxwell's equations, and 3D non-splitted NPML ABC is presented. Compared with the splitting PML, the NPML programs are less complex. The results show that the ABC is much simpler and easier to carry out in the FDTD computation. By the 3D numerical examples of electromagnetic scattering, the NPML ABC is verified. The results show that the ABC is a perfectly matched layer and it can be used in the actual target analysis of electromagnetic scattering problems.