The invention provides a popularity-based duplicate rating calculation method and a duplicate placement method which are applied in a distributed network. The duplicate rating calculation method comprises the steps of: obtaining popularity information of a file f in the local region; calculating the access probability of the file; obtaining access probability values of the files with highest popularity in the distributed files of the current region; and calculating the duplicate rating number L of the file. The duplication placement method is based on the result of the rating calculation, anda main node of the current file is found according to the DHT routing algorithm; the file, the corresponding duplicate rating and other related information are downloaded to local; and all the nodes of L site which are matched with an ID of the main node are found through a routing table of the main node, and the file is duplicated on the nodes. The methods obtain the duplicate rating number and the corresponding placement position of the file in a structural PSP network through the analysis and the calculation of the popularity of the data file and reasonably and effectively place data in the network, thereby reducing user access delay and improving the performances of a system.