The invention relates to a composite absorbent capable of removing hydrogen sulfide in oxygen-containing waste gas. The composite absorbent mainly contains the following components in percentage by weight: 15%-50% of component A absorbing H2S, 0.5%-6% of activating agent B, 0.1%-1% of antioxidant C, and the balance of desalted water. The working principle of the absorbent is low-temperature absorption and high-temperature regeneration, the side product is H2S gas with the concentration being greater than 95%, and the solvent can effectively prevent H2S from being oxidized into elementary sulfur by oxygen in the gas. The composite absorbent can achieve certain economic benefits while the problem of environment pollution is effectively solved.