A tent assembly has a supporting frame and a rainfly. The supporting frame has a top base and multiple supporting rod units. Each supporting rod unit has a top rod, a first joint, a middle rod, and two hooks. The first joint is connected with the top rod and has a pivotal center. The middle rod is connected with the first joint. The hooks respectively have an end pivotally connected with the first joint respectively at positions away from the pivotal center of the first joint. The rainfly is connected with the supporting frame and has multiple connection units. Each connection unit has multiple connection ropes and at least one elastic belt. The at least one elastic belt is mounted around the hooks of a corresponding one of the supporting rod units.