This paper presents a safety criteria method developed for the installation of left-turn phasing. To develop the safety criteria, six safety indexes are taken into account, namely, accident number, accident rate, accident severity, accident risk, conflict number and conflict proportion. By using the accident quality control method, the threshold of safety criteria is determined to calculate the danger score. Using danger score as the criteria, it can be becided which left-turn phasing type should be adopted. This paper also provides the worksheet of the safety criteria method for practical application.