3D technology for networks-on-chip (NoCs) becomes attractive. It is important to present an effective scheme for 3D stacked NoC router and interconnect testing. A new approach to testing of NoC routers was proposed by classifying the routers. Routers with different input/output ports fall into different classes. Routers of the same class are identical, whose tests are the same. A new unicast-based multicast scheme was proposed for the identical routers. A new test application scheme was proposed for interconnect testing. Experiments showed the effectiveness of the proposed method.