As optical networks evolve toward Software Defined Optical Networks（SDON）with higher speed and greater capacity

the scale of optical networks is also enlarged increasingly

which leads to the longer lightpath and accumulated optical signal degradation problems.In order to solve this problem

this paper proposes a Optical Signal Noise Rate（OSNR）awareness based lightpath optimization scheme in OpenFlow enabled SDON.This proposed scheme is able to take the OSNR factor into consideration and introduce OSNR factor into the lightpath establishment and wavelength allocation.Thus

the communication blocking due to low OSNR value can be avoided.Simulation results show that the proposed scheme can achieve better performance on successive rate of lightpath establishment under non-ideal networks.