1. A method for switching between memory banks in a native method invocation in a smart card, wherein a method return frame stores a status of a native method invocation, and a memory bank flag points a program counter to a runtime environment (RE) memory bank or an operating system (OS) memory bank, the method comprising the steps of: performing a method invocation; pushing the method return frame and setting the method return frame as the native method invocation when the method invocation is the native method invocation; using the memory bank flag to point the program counter to the OS memory bank; executing a native method, and popping the method return frame after the native method has been executed; and changing the memory bank flag to point the program counter to the RE memory bank if the method return frame is set as the native method invocation.