This paper presents designing and control method of Quadruped Locomotion Robot Leg using artificial muscle. The artificial muscle control is difficult because it contains nonlinearity and delay. Therefore, this study aims at establishing control method which consider nonlinearity and delay. First, we designed and fabricated robot leg of structure that antagonize artificial muscle. This paper proposes novel control method by using Generic Algorithm combine with the driving of periodic air pressure applying. Three evaluation functions were invented to identify optimization of leg trajectory. We conducted driving experiment using each evaluation function. According to comparing 8th generation with 1st generation, leg trajectory was changed by each evaluation function.