In this paper, we propose a distributed scheduling scheme for internet-of-things (IoT) wireless devices. The scheduling determination that maximizes overall sum rate of the network is formulated as an optimization problem, which is very challenging because there exists no centralized coordinator in the typical IoT network. To resolve this, we introduce the-state-of-the-art message-passing framework and develop a distributed scheduling algorithm based on it. Our simulation results verify that the proposed distributed scheduling algorithm considerably outperforms previous distributed approaches.