Abstract: A computer lock system with time-control function consists of a main program to supervise the right and time of using the computer system by authorized users, and a subprogram to process and store basic data such as the entry of the users for ID examination and the setting of time-limit for using the computer system. Said main program thereof, once checked by a BootRom chip on a protect card and executed in an operating system, will start an internal clock for time-control and a screen saver to keep the computer system locked in wait for the access of an authorized user passing the ID examination so as to protect the computer system from the illegal use of the crackers and secure the right of the users. When the time-limit of using the computer system is up, said main program thereof will restart said screen saver to keep the computer system locked again in wait for another legal user, thus efficiently protecting the right and regulating the time of using the computer system by the users.