AQM algorithm has many deficiencies, such as a large queuing delay, strong delay jitter, the rate of the data into and out the team not matched, and thus it always leads to data retention, loss and oscillation. Based on this, the M/M/m (n) queuing system thought based on the BLUE algorithm is introduced which is called PBLUE. The algorithm ensures the stability of the queue length according to equilibrium equation under stable state. Meanwhile, it increases the expansion factor and adjusts the router's cache for quickly recovering of the lost data. In the simulation, the improved algorithm reduced the packet loss rate and increased the bandwidth utilization and stabled the queue length.