A fast speed computer system power-on & power-off method, that is used to reduce an amount of main memory transferred and stored from a main memory into a second storage device, thus speeding up a speed of re-activation of a computer system from a hibernation state into a full speed operation state. Said fast speed computer system power-on & power-off method is applicable to various types of computer systems, and can be used to write in and load back data in cooperation with a random access processing technology. In addition, said method can be used to reduce extent of data loss and damage of said computer system due to a sudden power outage of said computer system.