The invention relates to a method and a system for storing mass data of the Internet of Things (IoT). The system comprises a plurality of data receiving nodes, a master node server and a database cluster. The method comprises the following steps of: (1) carrying out preprocessing on IoT data, and putting the preprocessed data in the database cluster consisting of a master node, slave nodes and the data receiving nodes; (2) creating sample records, which take sample elements as storage units, on the master node according to the static and dynamic information of the data in the database cluster; (3) after the sample records are encapsulated, sending the encapsulated sample records to all the slave nodes by the master node so as to be subjected to fragmentation processing and/or separated storage; and (4) after the slave nodes complete storage, uploading results to the master node, and updating the data in the database cluster by the master node, thereby completing storage. According to the method and the system, the cluster is extended by fully utilizing the existing storage technologies so as to store the mass data, the IoT data are divided into lightweight data and multimedia data, and particularly, a fragmentation strategy is adopted aiming at a large-scale amount of data, so that the time expenditure caused by the extension of a storage space is avoided.