Abstract: To study the different time effect of electrical stimulation on myofibrillar microstructure and eating quality of yak at postmortem. This article studied the electrical stimulation ( 21V, 50W, ES72, 90, 108s) and normal chilling ( NC 0⁴℃, wind speed 0.5m/s) , then determine the shear force, glycogen content and myofibrillar microstructure at 0, 24, 72, 120, 168, 216h during aging.And determine the pH and temperature of yak in 24h after postermortem. The results showed that electrical stimulation increased the rate of pH and temperature drop, and could prevent the cold shorten effectively. At the time postmortem, the shear force of ES&C was lower than NC. At 216h of the postmortem, the shear force of ES&C108s were higher than ES&C72s and ES&C90s ( p < 0.01) , were 7.77% and 14.29% higher than ES&C72s and ES&C90s. The degradation of glycogen was increased, the glycogen of ES&C were 37.45%, 48.52%, 52.58%, 60.43%, 58.79%, 50.48% lower than NC. Electrical stimulation destroied the myofibrillar microstructure. Conclusion: Electrical stimulation could shorten the aging time of yak and improve the tenderness.