the present invention discloses a method of distributing files over a network , which can attain a proper balance of transfer rates of active spanning trees used between a transmitting node and a receiving node and minimize the time taken for transferring a large file in a p2p environment by forming an optimal set of distribution trees with reference to the link costs between the transmitting node and the receiving node and distributing chunk files through the optimal set of distribution trees . the method comprises the steps of : forming a set of spanning trees between a transmitting node and a receiving node and forming a minimum cost tree group by the sum of the link costs of links constituting each of the spanning trees ; adjusting the transfer rate of each spanning tree belonging to the minimum cost tree group in accordance with the link cost of each spanning tree belonging to the minimum cost tree group ; and transferring chunk files through the spanning trees whose transfer rate is adjusted .