A warm-up method for a machine system including a machine component and a machine sensor configured to sense temperature of the machine component is provided. The method comprises steps of; A) activating the machine component to execute a warm-up operation for warming up the machine component; B) determining whether the machine component is warmed up based on a target temperature corresponding to the machine component and a temperature of the machine component that is currently sensed by the machine sensor; and C) when it is determined that the machine component is warmed up, making the machine component not execute the warm-up operation.