Estimating available bandwidth (EAB) is an important and challenging task for providing QoS support in wireless networks. Existing works on EAB did not consider cooperative communication which can improve available bandwidth of wireless networks. To fill this void, this paper studies the problem of estimating available bandwidth in cooperative multi-hop wireless networks, which is formulated as an optimization problem, called Cooperative Available Bandwidth Estimation problem (Coop-ABE). Given a new connection request, the Coop-ABE problem targets at finding the maximum available bandwidth that can be provided to the new connection subject to that existing flows are kept free from interference. We propose a centralized algorithm to solve the Coop-ABE problem.