This paper presents the calculation of the controller load of computer control network in a real system. The Calculation of the controller load is very important in order to aid the designer engineer to choose the suitable capacity of the controller for data size. The probability theorem is used to investigate the process of load calculation. The interpolation technique is used to get the function of the required data for the studied system. The calculated value is compared with the measured value to investigate the reality of the proposed method in calculating the load controller using probability theorem. The comparative study between the measured value and calculated value indicate the efficiency of the proposed technique.