This paper introduced a means of ablation/ temperature-field predictions in novel modified fiber reinforced phenolic resin. The organic fibre is equivalent to phenolic resin in the novel method of ablation/ temperaturefield predictions. It is shown that the organic fibre is similar with phenolic resin in thermophysical properties,and it also can be treated as resins during thermal analyses. Therefore,the ablation/ temperature-field predictions of organicfiber- based composite materials is achieved by utilizing the existing design strategies for resin-based ablative materials. Test results and application analysis support this method.