Abstract: To improve the effectiveness of resource reservation in network admission control,the implementation method and problem of QoS(quality of service) negotiation and resource reservation of IntServ(integrated services) recommended by IETF(Internet Engineering Task Force) were investigated based on the network calculus theory.Under the conditions of the given arrival curve,maximum delay and buffer size,two new optimal allocation schemes for network resources in IntServ were proposed.The formulas of calculating the desired rate and buffer size for these schemes were derived.The research results show that the proposed schemes can save network resources effectively and raise network utilization through the introduction of a piecewise linear service curve.