To study the fiber manufacturing used to coal fly ash, melting behavior of fly ash and mixed minerals were studied with coal ash sample (sub-bituminous coal). Minerals used to Limestone[including CaO(50 ~ 60wt%)] and Dolomite [including MgO(30 ~ 40wt%)] are reacted fluxing agents. By using the proper composition, melting temperature and fibrous temperature are decreased. It should be seen that silicate and aluminosilicate ae dissolved in inserting fluxing agents. Therefore, the composition of fluxing agents in the sample, fibrous temperature and melting temperature gave rise to a great effect on the physical properties of fiber namufacturing. Tests of the manufactured fiber were measured for the diameter(10 ~ 25 μm), tensile strength (200 ~ 350 kg/mm(2)) and Young's Modulus(5000 ~ 6000 kgs/mm(2)).