Firstly

we summarized the technical development trend of the optical transmission network in this paper.Secondly

we analyzed the main factors which influence the reliability and safety of optical transmission network;according to the familiar network model

from the equipments to the whole network system

and described the calculation process of the usability about optical transmission network in detail.Thirdly

we indicated the significance that build up the reliability and safety of optical transmission network with protection and recovering these two kinds of mechanisms.Finally we concluded the sensitivity of different factors which influence the optical transmission network

farther generalized the method which could carry out the different SLA of optical transmission network.