Active measurement has been a primary method used in network path bandwidth measurements to date,with greater flexibility and deployment convenience compared to the passive one. The available bandwidth measurement probe model is not precise enough for background traffic and problems with high error rate, so we define the communication protocol, detect packet structure, and propose the calculation method of the increase rate of sequence delays and the outlier range. The algorithm can reduce the interference of background traffic on the network path. The effectiveness of the algorithm has been verified by using NS2 simulation.