This paper investigates average access times on eight asynchronous priority levels of FDDI MAC protocol with parameters on offered loads, message sizes, and number of stations. In case of parameter with offered loads, higher priority levels exhibit similar variances and in case of parameter with message sizes and number of satations, higher priority levels exhibit almost invariables but as increase of message sizes, increase only a small amount of access time on the other hand, as number of stations increase, average access times decrease little by little. But in case of lowest priority level. average access times decrease little by little. But in case of lowest priority level, average access times exhibit relatively large variances about above three parameters.