Wireless ad-hoc networks are marked without a basic infrastructure and global information for the current status of the network. For multichannel slotted ALOHA systems of wireless ad-hoc networks, this letter proposes a (re)transmission control algorithm for the transmitters to employ. The algorithm aims at minimizing Lyapunov (negative) drift on the sum of all transmitters' queue, while it is implemented in a distributed way such that each transmitter only needs local information, such as the number of idle channels. To control (re)transmission probability optimally, with the local information, each transmitter solves a subproblem of estimating the number of backlogged nodes in each time slot. Simulation results show that our proposed algorithm yields near-optimal queuing performance.