This paper studied the thermal behaviour of pineapple leaf fiber (PALF) reinforced with polypropylene (PP) and polylactic acid (PLA) composite, used for natural fiber honeycomb core. Thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis were used to measure the thermal characteristic of PALFPP/ PLA composites. In particular, the TGA analysis was utilized to measure the degradation and decomposition of materials in different composition (NF-PP/PLA (0, 15, 30 and 50). The measurements were carried out in the temperature of 0&3x00BO;- 900&3x00BO;, at a heating rate of 10&3x00BO;min-1 and under an inert atmosphere (nitrogen gas). The temperature of DSC analysis was programmed to between 25&3x00BO;- 500&3x00BO;. The result shows the thermal stability of PALF-PP/PLA decreased as the PALF filler-loading increased. While from the DSC analysis this study clearly shows in the graph plot, the transition temperature, crystallization and melting temperature. So is crystalline and amorphous domains © 2021. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences.All Rights Reserved