Reaction mechanisms of Chlorella pyrenoidosa (CP) and textile dyeing sludge (TDS) co-pyrolysis were complex attributed to large activation energy variation. The maximum decomposition rate of CP/TDS co-pyrolysis presented a linearity (R-2 = 0.9960) versus blending ratio. Obvious synergistic effects had been found during co-pyrolysis at high temperature. The synergistic index of co-pyrolysis reached a maximum value ( = 3.92%) at a blending ratio of 50% CP and 50% TDS. The blending ratio of 20% CP and 80% TDS led to the minimum lowest synergistic index value ( = 1.34%), but decreased the apparent activation energy effectively.