We used exercise training rat as animal model, and investigated the effect of exercise training on the property of large-conductance Ca²⁺ voltage-activated K+ (BK) channels in VSMCs using patch clamp technique. The results showed that the open probability of channels increased significantly during the second and third week of exercise training, then became stable in the fourth week. After the exercise training, the sensitivity of channels to voltage and intracellular Ca²⁺ was enhanced, and its mean opening time got longer while the mean closed time got shorter. Our results also showed that the exercise training had no effect on channel conductance. These changes in biophysical properties of BK channels after exercise training could be considered to prevent membrane depolarization and vasoconstriction.