A cost-effective hierarchical porous polymer poly-methylbenzene (PMB) was produced using the most common organic compound methylbenzene via a simple one-step Friedel–Crafts reaction. The large surface area as well as the proper mesoporosity ensured it to be a good substrate for loading metal species. After the impregnation of various metal species including PdCl2, Ag+, Fe3+, Ni2+, Zn2+, Cu2+ and Mg2+, a series of efficient desulfurization adsorbents of metal/PMB-x were fabricated. Among them, the PdCl2/PMB-40 adsorbent showed a most promising desulfurization performance with the DBT adsorption capacity as high as 25.97 mgS/g and a second-order desulfurization rate. Fourier transform infrared spectra (FTIR) measurements confirmed the desulfurization mechanism as the formation of S–M binding and π-complexation. Both high surface area of PMB and highly dispersed PdCl2 nanoparticles contributed to the good desulfurization performance.