The invention aims to find out a hadoop distributed file system (HDFS) metadata storage method based on a relational data base capable of solving the problems in the prior art, quickly reading the data and storing more metadata. The HDFS metadata storage method based on the relational data base comprises the steps of: building the relational data base, building the memory storage, writing the metadata, and reading the metadata. The HDFS metadata storage method based on the relational data base is used for obtaining the following beneficial technical effects: the relational data base is used for storing the metadata information, and the frequently used data is stored in the memory; the data in the memory is preferentially inquired while reading the data, so the data is quickly read, and the problem of inadequate memory space caused by the inadequate memory can be solved; and after the firstly-written data is stored in the memory, the storage address is not the memory address directed by the head of a double linked list, but the memory address directed by the middle of the double linked list, so the duration time of backup data in the memory is reduced, and the utilization rate of the memory is improved.