A method for protecting a privilege level of a system management mode (SMM) of a computer system is disclosed. A SMM program is loaded into a special memory (SMRAM) area within a system memory of a computer. A first program, a second program, and a vector table are loaded into a general area of the system memory. Before the booting process of the computer has been completed, a reference hash value of the first program is determined by the SMM program, and the reference hash value is stored in the SMRAM area. A hash value of the first program is the computed by the SMM program. After the computer has been operating under an operating environment of an operating system, the computed hash value is compared to the reference hash value. When the computed hash value matches the reference hash value, the first program is called by the SMM program.