In this paper we present a flow control algorithm designed to improve the performance of ATM network and to gain higher throughput by guaranteeing negotiated cell loss ratio (CLR) for all cell streams passing through the usage parameter control (UPC). In particular, the cases in which a Tahoe, Reno, New Reno, and SACK schemes are applicable in peak-cell-rate (PCR) are discussed. The proposed algorithm improves the performance by adjusting the growth and the declination of window size, rather than using advertised window per se, by means of incoming traffic rate, number of cell drop, current window size and cell delay time. Several simulations are performed to study how different kinds of flow control algorithm behave when congestion existed and compared to our proposed algorithm. By varying advertised windows size in each algorithm, we can obtain the impressive results that support our algorithm.