Since nodes near the sink burden the data load for nodes far away in wireless sensor networks, its energy consumption is higher and easy to form the energy hole. In this paper, for cluster based heterogeneous wireless network in which the node with higher initial energy as the cluster head and nodes with lower initial energy as common nodes, the study proposes an energy hole avoid strategy by working with unequal cluster radius. The core idea of this strategy is that the cluster radius near the sink is smaller and cluster radius away from the sink is bigger, so that more cluster heads with higher initial energy are deployed near the sink, and then weaken the impact of energy hole, so as to balance the energy consumption. This paper aims at mitigating energy hole by deploying fewer nodes under the network lifetime constraint, and gives the detailed calculation and optimization method of the unequal cluster radius values. Theoretical analysis and experimental results show that the strategy in this paper has greatly improve the network lifetime and performance, and can be a good guidance for deployment of heterogeneous wireless networks.