A method of computerized optimization system of radiotherapy treatment planning is presented. For the optimization of treatment planning, it is highly desirable to evaluate treatment planning quantitatively corresponding to a set of three-dimensional criteria. For this purpose, we introduce a set of criteria using some parameters defined as three-dimensional extension of those of ICRU report 29. The development of computer software has become feasible for clinical use of our criteria. This paper described some preliminary results of our criteria which was applied to some clinical cases. Our method was proved applicable to any type of treatment plannings, and the optimization of treatment plannings will surely be realized through our criteria.