Wired local network is used widely in a vehicle. It brings the benefits of sharing information and controlling automatically as well as causes negative reaction and a troublesome problem to vehicle such as weight, cost, electromagnetism and space and so on. Infrared optical wireless communications are an alternative way to break through these limitations for increasing safety, decreasing fuel consumption and high bandwidth. In this letter, we address the issue of design a wireless network in a vehicle with an infrared link and ring topology. We discuss the performance requirement of the network, and analyz its bandwidth, power, link distance choice and message schedule. At last, we simulate the preferred parameters of an optical link system.