We prepared a kind of metal oxide-modified walnut-shell activated carbon (MWAC) by KOH chemical activation method and used for PH3 adsorption removal. Meanwhile, the PH3 adsorption equilibrium was investigated experimentally and fitted by the Toth equation, and the isosteric heat of PH3 adsorption was calculated by the Clausius-Clapeyron Equation. The exhausted MWAC was regenerated by water washing and air drying. Moreover, the properties of five different samples were characterized by N2 adsorption isotherm, SEM/EDS, XPS, and FTIR. The results showed that the maximum PH3 equilibrium adsorption capacity was 595.56 mg/g. The MWAC had an energetically heterogeneous surface due to values of isosteric heat of adsorption ranging from 43 to 90 kJ/mol. The regeneration method provided an effective way for both adsorption species recycling and exhausted carbon regeneration. The high removal efficiency and big equilibrium adsorption capacity for PH3 adsorption on the MWAC were related to its large surface area and high oxidation activity in PH3 adsorption-oxidation to H3PO4 and P2O5. Furthermore, a possible PH3 adsorption mechanism was proposed.