Heat barriers or insulators were defined as those materials or combinations of materials, which retarded the heat transfer with reasonable effectiveness under ordinary conditions. Insulating materials were used in many different applications and at a variety of temperatures. The purpose of thermal protective clothing is to reduce the rate of heat build up in human skin, in order to provide time for the wearers to react, and avoid or minimize skin burn injuries. This is accomplished by using a garment which is both flame resistant and thermally insulating. Many of the heat barrier materials being employed use some form of textile fibers or fabrics. Firefighting protective clothing is a highly advanced system designed to protect people against being burned in high temperature environments. This research focuses on the development and evaluation of firefighting fabrics use in flash-over temperature approximately1000℃.The overall design of the isolated flexible composite fabric was compounded of inner comfort layer, phase changes endothermic composite layer and outside heat reflecting layer, sequentially, in order to achieve a flexible, efficient, long-term effect of thermal protection. To give a brief introduction to the preparation and process of the flexible composite fabric, the high temperature environment, severe heat, the fire incident due to radiation intensity, and relatively high temperature thermal properties of the fibers were considered.Metal foil has a high thermal the reflectivity and low cost-effective; therefore aluminum foil was used as a heat-reflective material, bonded to a high-temperature glass fabric. The nonwoven basalt fiber and nonwoven glass fiber fabric were selected due to their high performance under high temperature environment. Two stages of phase change materials were selected to design the flexible composite fabric. The Galactitol was chosen as the first stage phase change material and NaCl-MgCl2as the second stage phase change material in the composite fabric. The design principle considers some parameter such as phase change material phase change before and after the relatively fixed, the choice of the high temperature resistant fibers needled felt and phase change as the endothermic composite layer matrix. The firefighting composite fabric substrate on the outer layer heat-reflective layer, selection of high performance fiber, based on two phase change materials which are safe to use and easy to get. In order to ensure human comfort, the retardant cotton fabric was selected as the inner layer. To ensure the composite fabric flexibility, as well as the phase change material is relatively fixed, the sewing processing of each of the functional structural layers of composite was formed.To characterize the fabric insulation performance under the flash-over conditions and its prolonged failure behavior, fabric samples were placed in this environment, and the temperature sensors were used to measure the specimens’ positive and negative temperature changes with the time. The temperature-time curves were obtained through computer control software for real-time recording, to measure and compare the pros and cons of the firefighting fabric’s insulation performance. In addition, repeated exposure to open flame fire environment fabric thermal protective performance and retention of the basic mechanical properties test analysis.The obtained composite fabric having excellent fire insulation properties, the composite fabric composed of functional decomposition due to their respective monolayer sharing role. This fabric design has a better fire insulation effect by the test of fire insulation performance of the flexible composite fabric.From the analysis of the heat transfer model and the measured results of the fire insulation performance, it is shown that the treated firefighting fabrics under the environment of high temperature and severe heat, is difficult to achieve long time protection. The high temperature phase change materials during the fire exposure experiment and it is efficiency play significant role in the fire protective performance of the composite fabric. The adiabatic test system heat transfer model in fabric thermal performance parameters vary with temperature of the heat transfer mechanism needs to be further explored. So long, high-temperature differential drop firefighting fabric development and its mechanism of heat transfer and much work remains to be done in-depth research.