An auto scaling method including: when the tenant needs to complete auto scaling for a scaling group of the tenant, the cloud management platform may receive, through a network interface, an auto scaling formula that is input by the tenant for the scaling group. Then, the cloud management platform may obtain a current load indicator of the scaling group, and substitute the current load indicator of the scaling group into the variable that indicates the current load of the scaling group and that is in the auto scaling formula, to obtain a target capacity of the scaling group. Finally, the cloud management platform may adjust a quantity of cloud instances included in the scaling group, until a capacity of an adjusted scaling group matches the target capacity of the scaling group.