The B-ISDN should handle the many channel set up requests implicit in multimedia services, and the trend toward reduced transmission cost is expected continue into the future, thus making the node cost relatively high. So it is necessary to simplify both node functions and transport network architecture. To do this, The concept called ``virtual path`` has been proposed. The effectiveness of virtual paths can be extended by dynamic path controls such as dynamic path bandwidth allocation, which improves the transmission efficiency. For this, a simple dynamic bandwidth control algorithm has been proposed. For implementing the simple dynamic bandwidth control algorithm, several control parameters, that is, bandwidth change steps, should be determined. The performance of the network which employs the dynamic bandwidth control mostly depends on selection of these parameters. In this thesis, using the call loss probability as the measure of performance, we propose an algorithm to determine the bandwidth change steps which improve the performance of network. Finally, we evaluate our algorithm by simulation.