This work is dedicated to design the dose field uniformity of irradiation facility installed 576 cobalt sources sticks by use of Monte Carlo method and MATLAB language. By comparing calculations with measurements the further calculation of dose distribution in the irradiation facility was performed by setting 3200 tally points of irradiation doses. In order to obtain the optimum data employed in our study, numerous position adjustments of the cobalt source sticks were made to calculate the dose distribution of the irradiation facility. And it had been found that there was a good agreement between program calculations and the measurements. The dose uniformity of irradiation facility and the efficiency of energy usage will be greatly increased after adjusting the cobalt source sticks according to the calculated results.