A seawater desalination system is provided using a jet technique, which comprises a filter apparatus, a sonic energy treatment apparatus, and a desalination apparatus. After being coarse-filtered and fine-filtered, the seawater enters the sonic energy treatment apparatus. After being treated by the sonic energy treatment apparatus, the seawater is stored in a water storage tank in the form of small molecular clusters, and then pumped into a reverse osmosis membrane. After osmosis, the water becomes freshwater and stored in a freshwater tank. During the process, the reverse osmosis membrane can be replaced by a distillatory. The system has the advantages of a simple structure of the seawater desalination apparatus, less investment, low cost, and stable performance. The seawater is not only desalinated, but also chain-shortened into water of small molecular clusters, which is easily absorbed and utilized by human body.