In the design of Wireless Mesh Network (WMN) for small cell backhaul, deployment cost and reliability are important considerations and are mainly determined by network topology. Reliability ensures the network quality for clients and cost is a major concern in telecom operators. In practice, increasing redundant network links improves the reliability of a backhaul network, but increases the cost substantially. Generally, network reliability and cost are considered separately. In this paper, we propose two algorithms based on minimum spanning tree (MST) and the shortest path (TSP) constructing reliable backhaul infrastructure that resists the disabled single mesh nodes with low cost. Via a case study, we show the relationship between deployment cost and reliability. The proposed optimization model provides the backhaul network operators with reliable and costs trade-off solutions and compared deploy cost in different bandwidth.