MIMO is an emerging technology which can substantially increase the link capacity of wireless communications. MIMO has also been shown to enhance the throughput in the coexistence of heterogeneous wireless networks due to its capability of performing spatial-multiplexing (SM) and interference cancellation (IC). Practical protocols such as 802.11n+ have been proposed to address the coexistence problem in MIMO wireless networks. However, all the previous work focused on the physicallayer or MAC-layer design. None of them studied the networks’ incentives to comply with or violate the low-level protocols. In this work, we study the coexistence of two single-link MIMO wireless networks with IC and SM capabilities, by analyzing their incentives of cooperation or non-cooperation (whether they will use their available degree-of-freedoms to cancel the interference to each other). We propose a novel two-round game framework, based on which we derive two networks’ strategies in equilibrium and the corresponding closed-form utilities. We obtain numerical results of the equilibrium strategies under different network scenarios. Several insights are gained, which can guide us the design of real-world MIMO wireless systems in the future.