The electromagnetic losses of nickel waveguides in the submillimeter wave frequency band are measured, and a waveguide terminator based on nickel Spoof Surface Plasmon Polaritons (SSPPs) is designed for multi-port waveguide device measurements and power divider port isolation. The waveguide employs a simple and compact antisymmetric rectangular probe structure to efficiently couple electromagnetic energy from the waveguide to a microstrip, which is then transmitted to a comb-like SSPPs terminator. The microstrip circuit and SSPPs circuit are fabricated on a quartz substrate, with the metal circuit being electroplated metal nickel. Utilizing the band-stop characteristics of SSPPs and the high-frequency high-loss properties of metal nickel, the attenuation and absorption of electromagnetic energy are achieved. The proposed nickel SSPPs waveguide terminator is experimentally validated in the W-band (75~110 GHz). The experimental results indicate that the Return Loss of this waveguide terminator exceeds 15 dB across the entire W-band, with a corresponding electromagnetic absorption rate of over 96.8%.