Abstract: In underlay cognitive radio scene, secondary users can opportunistically access the licensed spectrum under the constraint of interference temperature. In this paper, Stackelberg game is adopted for allocating power resource. In this model, the primary user acts as leader, secondary users act as followers. When using the licensed spectrum, secondary users must make payments to the primary user based on the induced interference power to the primary user. Meanwhile, the primary user aims at maximizing its own revenue through adjusting its price, under the constraint of interference temperature. Given specified price, the secondary users compete with each other using the non-cooperative game theory. Simulation shows that, compared with the centralized optimal power allocation algorithm, the proposed distributed power allocation algorithm not only can achieve close-to-optimal performance, but also needs much less communicating overhead than the optimal algorithm which is very beneficial.