In this study, a novel halogen-free flame retarded form-stable phase change material (PCM) was designed and prepared, selecting paraffin as the thermal-energy storage material and epoxy resin (EP) as the supporting material; furthermore, a novel flame retardant curing agent PEPA-TMA (2,6,7-trioxa-1-phosphabicyclo-[2.2.2]-octane-4-methanol reacted with trimellitic anhydride) and melamine cyanurate were combined into the energy-storing material to obtain the flame retarded PCM. Thermal performances of the PCM were investigated through differential scanning calorimeter, the data suggested that the PCM had relatively high latent heat, and values normalized to the amount of paraffin were lower than the theoretical values. The thermogravimetric analysis displayed that the intumescent flame retardant (IFR) could improve the charring of the PCM, and the PCM had passed a UL 94 V-0 test when the IFR loading reached 24 wt%. The cone calorimeter results further proved that the PCM had better flame retardancy. The morphology of the composites was observed by scanning electron microscopy, and the images showed that the paraffin could be dispersed uniformly in the materials, which formed a three-dimensional network by EP.