The invention discloses a load creating method, a deactivation method, a service gateway and a mobile communication system in SAE (System Architecture Evolution). The load creating method comprises the following steps of: receiving a load creating request of a first network element by the service gateway; transmitting the load creating request to a second network element by the service gateway; receiving a response of successful load creation from the second network element by the service gateway; and when the service gateway fails to process the load creation, sending a deleting request to the second network element. The method, the service gateway and the system fundamentally solve the problem of residual loads of relevant network elements, caused by various reasons, by optimizing the flow of the traditional default load and the special load and adding the initiative starting user deactivation flow of the service gateway.