Abstract: The landfill and incineration of waste plastics produce pollutants such as microplastics and dioxins, seriously endangering the ecological environment. The efficient and environmentally friendly recycling of waste plastics is one of the serious environmental problems in China. The co-pyrolysis of plastic with biomass is an important way to utilize plastics, and the key challenge of this technology is to improve the gas production rate and reduce the secondary pollution. In this work, the polypropylene (PP) and Salix psammophila (SP) were selected, and the impregnation method was used to prepare Co-ZSM-5 catalyst. The effects of co-pyrolysis and catalytic pyrolysis at 400–600 ℃ were explored and the gas production characteristics and polycyclic aromatic hydrocarbons (PAHs) generation were investigated. The results indicate that with the increase of the temperature, the yield of product gas and PAHs gradually increase, and there is no solid residue in PP pyrolysis after 500 ℃. Co-pyrolysis and co-catalytic pyrolysis can reduce the yield of tar and PAHs. However, at 500 °C, the productions of fatty hydrocarbons and alcohols in co-pyrolysis tar increase by 5.2% and 10.9%, respectively. The addition of catalysts further increases the relative content of fatty hydrocarbons and alcohols in tar at low temperatures. The toxicity equivalent of PAHs decreases significantly under co-pyrolysis and co-catalytic pyrolysis. At 600 ℃, the toxicity equivalent decreases by 9.3 wt% and 50.4 wt%, respectively. However, at 900 ℃, the addition of catalyst increases the production and toxicity equivalent of PAHs during the co-pyrolysis process of PP and SP.