The mass loss rate and heat release rate of puzzle mats were analysed using variable external irradiation level. Five samples of puzzle mat were tested in this study : Type A, B, C, D and E. Type A, B and C are all general grades whereas Type D and E are both Flame retardant grades. Incident heat fluxs of $25kW/m^2$, $35kW/m^2$, $50kW/m^2$ and $70kW/m^2$ were selected for these experiments. All samples were tested in the horizontal orientation and were wrapped in a single layer of aluminum foil. Each sample was nominally 20mm thick and 100mm square. The combustion heat and mass loss rate were carried out from Oxygen bomb calorimeter and mass loss calorimeter according to ISO 5660-1 respectively. Heat release rates were calculated using the equation ${dot{Q}}=A_f{dot{m}}"_X{Delta}H_c=0.75A_f{dot{m}}"{Delta}H_c$. where $A_f$ is the horizontal burning area of the sample, $dot{m}"$ is mass loss rate per unit area, ${Delta}H_c$ is complete heat of combustion and 0.75 is combustion efficiency.