Due to the rapid growth in digital control technology because of their great advantages, it now possible to consider implementing a digital programmable controller for many industerial processes. In this paper some software aspects of digital controllers for temperature control loop in crude oil refineries have been discussed and a new method has been developed for rapid tuning of these controllers'parameters through the implementation of digital simulation technique. Different structures of the control loop have been investigated with main emphasis is given to cascaded and feedforward/feedbackward loops. Cascaded structures is shown to reduce the effect of the time delays and yield better dynamic character-istics for the control loop. Preview of the future system disturbance inputs through the feedforward path is shown to be effective to improve the performance of the overall control system. The results of the present investigation indicate that the proposed method is capable to detune the parameters of each controlling action either on-line or off-line with sub-stantial improvement in the dynamic performance of the control loop. Illustrative examples as well as practical applications are also included.