<p>Collection delivery points (CDP) delivery is an effective method that saves more cost in last-mile logistics. CDP networks have become the important partners of express firms in last-mile logistics and some of them have grown into large brand enterprises. In this context, the large brand CDP network is no longer satisfied with merely supporting the incumbent express firm and has incentives to encroach on the express market by building their express business. As a response, the incumbent express firm will stop cooperating with the large brand CDP network and switch to an alternative small brand CDP network to counter the encroachment. We build a game model to examine the encroachment strategy of the large brand CDP network and whether the incumbent express firm should switch to an alternative small brand CDP network considering the encroachment. Interestingly, when CDP delivery can’t save the logistics cost largely and the profit space of express business is relatively small, the large brand CDP network will still encroach on the express business. Furthermore, we find that switching to an alternative small brand CDP network is not always an effective strategy against the encroachment. This study provides managerial insights for CDP networks with options to encroach on the express market.</p>