The interactions of polyvinyl chloride (PVC) and biomass components (hemi-cellulose, cellulose and lignin) during fast pyrolysis were investigated at 800°C in a fixed bed reactor. The interactions of PVC and biomass components decreased the HCl yield and increased the tar yield significantly. During the co-pyrolysis of PVC with the biomass components, most polycyclic aromatic hydrocarbon (PAH) components were decreased compared with the calculated proportion results. The mechanism of the interactions may be that in the fast pyrolysis process, the processes of dehydrochlorination and chain scission occur in a very short time. Biomass materials and/or bio-char can act as catalysts which inhibit the dehydrochlorination process or promote the chain scission of PVC. Therefore, the dehydrochlorination process might not be completed, resulting in the production of chlorinated oil compounds. Thus, the HCl yield is reduced and PAH concentrations are decreased during the co-pyrolysis of PVC and biomass.