In this study, a Cu–Fe–Ce composite metal oxide adsorbent was synthesized by chemical precipitation method to simultaneously remove H2S and PH3. The effects of reaction temperature, oxygen content, gas inlet concentration and gas hourly space velocity (GSHV) were studied. The DRIFTS results showed that excessive oxygen and high reaction temperature lead to excessive conversion of H2S, which competed with adsorption–oxidation of PH3, and it was not conducive to simultaneous removal of H2S and PH3, and it was found that high concentration of H2S was more likely to cause deactivation of the adsorbent than PH3. GHSV affected the contact time between the adsorbent and the gas and affected the removal effect. The BET results showed that a larger specific surface area was more conducive to gas adsorption, and thus had a better removal effect. The XPS results showed that the deactivation of the adsorbent was due to the formation of sulfur-containing and phosphorus-containing substances.