The priority based source and destination initial reservation protocol (PSDIRP) is put forward in wavelength division multiplexing, which is aimed at solving the optical resource reservation for multiple connection requests arriving at the same time. The source-destination initialized reservation protocol is proposed to improve the reservation efficiency. The least utilization rate of wavelengths by the Markov model to determine the available resource factors of multiple requests is got. The algorithm sets the priority and the wavelength assignment model combining with the connection requests′ characteristics, such as total load factor (TLF), through the way of combination of serial control and parallel control. From the simulation, it is can concluded that the algorithm has a better performance in the increase of the resource reservation ratio and the optical network resource utilization rate comparing with the traditional algorithms.