Initial crystalline and crystalline change under isothermal crystallization and various aging conditions are studied by Differential Scaning Calorimeter (DSC) and Modnlated DSC (MDSC). The initial crystalline is very small from our experiments and crystalline tested by DSC results from thermal relaxation and subcooling crystallization. Isothermal crystallization rate at 80 ℃ is the fastest, which is about the 0.85 T_m(melting temperature); crystalline of F₂₃₁₄ increases while aging at different conditions, longer time and high temperature will result in more crystalline.