According to the intersection with low bus flow rate, an optimal control system of intermittent bus-only approach was proposed. This paper firstly put forward an improved method for the existing system: the performing time of control system was advanced to guarantee the bus priority, the instant when intermittent bus-only approach was available to general traffic was controlled dynamically to increase the approach space utilization. Then the general traffic delay at intersection was analyzed quantitatively after performing the optimized system. The results show that the optimal control system of intermittent bus-only approach can reduce more general traffic delay than the existing system while guaranteeing the bus priority, especially when bus reaches the intersection during the red time, the delay reduction is more obvious.