The work aims to study the main components (paper fiber, low-density polyethylene and aluminum foil) in Al-PE-Pa complex packaging and analyze their interactive effect during hydrothermal liquefaction. At 360 °C and 20 MPa, the micro reaction still was used to conduct hydrothermal liquefaction reaction on paper fiber, low-density polyethylene and aluminum foil samples of single component, bi-component and three-component for 30 min to characterize the oil product yield, element composition, constituent and solid residue morphology, etc. The results showed that the bio-oil yield of the single-component paper fiber was 13.67%, but its oxygen content was as high as 24.19%. The single-component of low-density polyethylene (LDPE) was barely depolymerized at this condition. The yield of bio-oil (14.88%) was significantly higher than the theoretical yield (10.75%) of simple addition of single components. The hydrocarbon products in the oil were significantly increased. Ketones, esters and alcohols were all reduced. Aluminum foil could significantly reduce the oxygen content of the bio-oil from paper fiber, increase the heating value of the bio-oil, and significantly reduce the ester and phenol contents in the bio-oil. The bio-oil yield of three-component paper fiber, LDPE/aluminum foil increased from the theoretical calculated value of 10.21% to 19.00%. The high heating value increased from 28.80 MJ/kg to 30.04 MJ/kg. The oxygen content of oil decreased to 21.76%. And the ketones in the product components decreased significantly from 28.12% to 8.96%. Co-liquidation of paper fiber and LDPE has synergistic effect. The aluminum foil achieves site hydrogenation of oil products at hydrothermal conditions. The co-liquefaction of three-component paper fiber/LPDE/aluminum foil has superimposed effect of the synergistic effect of paper-plastic synergy and in-situ hydrogenation of aluminum-water reaction.