Abstract: Aiming at the problems of high storage cost, low reliability, and insufficient node load balancing capacity caused by ignoring the difference between storage nodes in a cloud storage, we propose a fragment sort swap algorithm (FSSA). First, we establish a mathematical model for the data block placement problem. Then, we divide the fragments according to the load condition of each node and select the nodes according to the requirements of data reliability in each segment. Finally, according to the analysis of the objective function in the mathematical model, we select the appropriate nodes in the segmentation result to place data. The simulation results show that the proposed FSSA algorithm can reduce data storage cost and enhance system load balancing ability in addition to ensuring the reliability of data storage.