Abstract: In this paper, the composition and content of organic matter in the effluent of anaerobic treatment and aerobic treatment of eucalyptus chemical mechanical pulp wastewater were analyzed by GC-MS method. The analysis of number of carbon atoms in the wastewater before and after aerobic treatment was counted, and the main bio-refractory components and degradation rules in the wastewater were analyzed. The results showed that the main residual organic pollutants after anaerobic and aerobic treatment were linalool (C10, 21.21%), methyl p-tert-butyl phenylacetate (C13, 21.39%), dihydromyrcenol (C10, 8.90%), lilial (C14, 6.16%) and citronellol (C10, 4.76%), etc, mainly containing benzene ring organic matter and bacteriostatic components, with biological refractory degradation and bacteriostatic properties. The macroscopic performance was that the removal rate of biological treatment was low. Before and after aerobic treatment, the mass fraction of alcohols in wastewater increased from 19.32% to 51.71%, the mass fraction of aldehydes increased from 3.68% to 13.35%, the mass fraction of esters decreased from 29.75% to 28.32%, and the mass fraction of benzene-containing organics increased from 32.70% to 61.06%, indicating that other organics were degraded more greatly than benzene-containing organics. It was recommended to improve the biological treatment effect by detoxification pretreatment and bioaugmentation to improve microbial activity, reduce the difficulty of subsequent deep treatment, reduce the cost of comprehensive treatment, and achieve low-cost discharge.