The invention relates to a method for preparing a filter paper fiber carrier for white-rot fungus culture. The carrier can be used for effectively guaranteeing the biological activity of white-rot fungi, is high in environmental tolerance and meanwhile is more suitable for determining the optimal reaction concentration, so as to achieve the aims of reducing cost and increasing efficiency. The method comprises the steps: chopping filter paper, soaking the chopped filter paper with water, mixing the filter paper solution and an ultrasonic treatment solution together according to the volume ratio of 1: 1, and carrying out ultrasonic treatment so as to enable filter paper fiber melted size to be uniform in dispersion and be milky; and then, carrying out freeze drying, dissolving the freeze-dried filter paper fibers and an agarose culture medium in pure water together, carrying out uniform mixing, carrying out high-temperature sterilization so as to obtain a crude composite fiber structure, submerging the crude composite fiber structure in a white-rot fungus fungal solution, and carrying out shaking-table culture. The method disclosed by the invention is advanced and scientific and is easy in operation, the prepared filter paper fiber carrier for the white-rot fungus culture is effectively applied to biological paper-pulp papermaking, the pulping efficiency is high, no environmental pollution is caused, and the cost is low.