A cloud file transmission method in a cloud computing system, the cloud computing system comprising a cloud server and a terminal, wherein the method comprises: receiving (S 101), by the terminal, a request for obtaining a file, wherein the request comprises a file identifier of the file; obtaining, by the terminal, first information by using the file identifier and an established first association relationship between the file identifier and the first information; sending, by the terminal, the first information to a cloud server, whereby the cloud server finds a saved file according to the first information and an established second association relationship between the file and the first information; and receiving, by the terminal, the file sent by the cloud server; wherein the method further comprises: receiving, by the cloud server, the first information sent by the terminal; searching, by the cloud server, for a saved file according to the first information and an established second association relationship between the file and the first information; and sending, by the cloud server, the found file to the terminal; wherein the first information is a check result generated by performing calculation on the raw data of the file by using a check algorithm, or wherein, the first information is a message digest result generated by performing calculation on the raw data of the file by using a message digest algorithm; wherein the file identifier is a file name of the file; and wherein the first information is generated by performing calculation on raw data of the file, and the raw data is data that can distinguish the file from another file; and wherein the first information is specifically a check result generated by performing calculation on the raw data of the file by using a check algorithm, or wherein, the first information is a message digest result generated by performing calculation on the raw data of the file by using a message digest algorithm. receiving (S 101), by the terminal, a request for obtaining a file, wherein the request comprises a file identifier of the file; obtaining, by the terminal, first information by using the file identifier and an established first association relationship between the file identifier and the first information; sending, by the terminal, the first information to a cloud server, whereby the cloud server finds a saved file according to the first information and an established second association relationship between the file and the first information; and receiving, by the terminal, the file sent by the cloud server; wherein the method further comprises: receiving, by the cloud server, the first information sent by the terminal; searching, by the cloud server, for a saved file according to the first information and an established second association relationship between the file and the first information; and sending, by the cloud server, the found file to the terminal; wherein the first information is a check result generated by performing calculation on the raw data of the file by using a check algorithm, or wherein, the first information is a message digest result generated by performing calculation on the raw data of the file by using a message digest algorithm; wherein the file identifier is a file name of the file; and wherein the first information is generated by performing calculation on raw data of the file, and the raw data is data that can distinguish the file from another file; and wherein the first information is specifically a check result generated by performing calculation on the raw data of the file by using a check algorithm, or wherein, the first information is a message digest result generated by performing calculation on the raw data of the file by using a message digest algorithm. receiving, by the cloud server, the first information sent by the terminal; searching, by the cloud server, for a saved file according to the first information and an established second association relationship between the file and the first information; and sending, by the cloud server, the found file to the terminal; wherein the first information is a check result generated by performing calculation on the raw data of the file by using a check algorithm, or wherein, the first information is a message digest result generated by performing calculation on the raw data of the file by using a message digest algorithm; wherein the file identifier is a file name of the file; and wherein the first information is generated by performing calculation on raw data of the file, and the raw data is data that can distinguish the file from another file; and wherein the first information is specifically a check result generated by performing calculation on the raw data of the file by using a check algorithm, or wherein, the first information is a message digest result generated by performing calculation on the raw data of the file by using a message digest algorithm.