Cooperative spectrum sharing is an effective way to improve energy and spectrum efficiency of wireless communication network. In this paper, we consider a power constrained cooperative spectrum sharing network and model it as a labor-consumption market. The secondary users (SUs) offer labor, i.e., power consumed for relaying the primary user's (PU's) traffic. In order to encourage SUs to work, PU admits SUs' consumption, i.e., the licensed band accessed by SUs for their own traffics. We formulate the problem as an auction in a labor-consumption market repeatedly played with multiple SUs for power and time trading in cooperative spectrum sharing. Based on this model, our results show that the performances of the PU and the network are greatly improved by cooperative spectrum sharing. Moreover, the selection of SUs depends on not only their channel conditions but also their transmission needs.