This letter suggests a modified priority scheduling policy for the asynchronous transfer mode (ATM) multiplexer, which is called DQLT. In the dual queue length threshold (DQLT) method, there exist two queues: 1) Q(1) is for nonreal-time traffic and 2) Q(2) is for real-time traffic and each queue has its own threshold to adaptively control the buffer congestion. If Q(1) is congested over the threshold T(1), one cell at the head of Q(1) moves into Q(2) in a slot time. It is shown that the DQLT method gives intermediate performance between those of minimum laxity threshold (MLT) and queue length threshold (QLT) policy, but its control method is quite simpler.