The aim of this study was to discuss the thermogravimetric kinetics of Tetra pak/high-density polyethylene flame retardant composites. In this paper, a wood/plastic composite with good properties was developed by extrusion followed by injection moulding using TPP waste and high-density polyethylene as raw materials, ammonium polyphosphate and melamine as intumescent fire retardants, and basalt fiber as a reinforced phase. Dynamics of thermal degradation of the developed composites was investigated by thermogravimetric analysis at 20~700 ℃ in the heating rate of 5, 10 and 20℃/min under N2 atmosphere. The Kissinger method showed that the activation energy of basalt fiber reinforced Tetra-pak/HDPE fire retardant composites was higher than that of the composites without any basalt fiber, demonstrating that the thermostability of Tetra-pak/HDPE fire retardant composites could be improved by the incorporation of basalt fiber into the Tetra-pak/HDPE matrix. The kinetic parameters and equations were also obtained by Coats-Redfern method for the basalt fiber reinforced Tetra-pak/HDPE fire retardant composites, and the results showed that the apparent activation energy of the first and the second thermolysis stage was 35.26 kJ/mol and 171.16 kJ/mol, respectively. The developed composite could be used as an alternative raw material in construction, packaging and other application fields. The utilization of Tetra pak packaging waste for value added products should be considered as new approach for paper/plastic/aluminum waste management and prevention of municipal solid waste environmental pollution.