Collaborative knowledge creation is important for firms to maintain and gain new competitive advantages, but knowledge outgoing spillover harms their competitive advantages, which puts them into a dilemma when making knowledge creation decision in innovation network. In this paper, the collaborative knowledge creation in innovation network is modeled as a Stackelberg leader-follower game with one core firm and multisubordinate firms. We discuss the knowledge input decision and knowledge output allocation of network members by introducing the knowledge incoming spillover coefficient, private knowledge, knowledge outgoing spillover loss and other variables. Through the analysis, we find that: 1) The core firm and the subordinate firm's knowledge input rate and the total amount of knowledge input are related with gains from collaborative knowledge creation fruits and knowledge incoming spillover profit, but are not related with private knowledge outgoing spillover loss; 2) The condition that the collaborative knowledge creation mechanism in cluster innovation network runs is that the core firm's knowledge creation profit (i.e. gains from knowledge creation fruits and knowledge incoming spillover profit) is big enough; 3) The core firm's knowledge input rate is positively related to its marginal gain and the knowledge incoming coefficient, and it is negatively related to the subordinate firm's marginal gain and knowledge incoming coefficient; 4) In the process of collaborative knowledge creation, the subordinate firms will allocate the investment rate of knowledge according to the marginal gain and the knowledge incoming coefficient.