This work comparatively studied the catalytic effect of MgO and MgCO on pyrolysis of rice husk (RH). The apparent activation energy (E) was reduced significantly by pyrolysis of RH with MgCO, thus lowering the decomposition temperature during pyrolysis. MgO could not obviously influence the gas evolution during pyrolysis, while MgCO had a better performance on the syngas (H and CO) generation at around 600-700 °C. Also, the generation of CO was suppressed by the RH pyrolysis with MgCO. The phenols were the dominant compounds in the bio-oil derived from RH. Furthermore, co-pyrolysis of RH and polyvinyl chloride (PVC) in the presence of MgO or MgCO at 600 °C could improve the oils quality by decreasing the acids content and increasing the hydrocarbons content. Particularly, the resulting oils had high hydrocarbons content (>35%) and low acids content (<2%). The decrease of acids, alcohols, and phenols contributed to the increase of hydrocarbons.