A method for resource allocation and a terminal device are provided. The method includes the following. An operating system first identifies an internal running scenario of a target application running in a foreground of a terminal device. The operating system then acquires a plurality of resource adjustment strategies associated with preset system resources to-be-adjusted in the internal running scenario. The operating system acquires status information of the internal running scenario. Thereafter, the operating system adjusts usage priorities of the plurality of resource adjustment strategies according to the status information. The operating system adjusts the preset system resources to-be-adjusted by selecting a resource adjustment strategy with the highest priority.