The consensus is that alliance partner selection plays an important role in alliance management, however little attention has been paid to its effect on the core knowledge protection as a risk control method. This paper studies the effects of enterprise knowledge protection capacity on the alliance partner selection under the different conditions of academic resource acquisition and non-academic resource acquisition, and proposes nine hypotheses.. The research results show that: under the condition of academic resource acquisition, firms tent to the order of friends >acquaintances > strangers to choose their partners when they have strong knowledge protection capacity; while firms tent to the order of friends >strangers >acquaintances to choose their partners when they have week knowledge protection capacity; under the condition of non-academic resource acquisition, firms tent to the order of friends >acquaintances > strangers to choose their partners no matter they have strong knowledge protection capacity or not. The conclusions of the studies not only enrich the relevant theories on the relationship between enterprise knowledge protection capacity and alliance partnershipselection, but also are instructive to the practice of enterprise alliance.