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SONG (Stellar Observations Network Group) is an international collaboration project involving many countries. Chinese stellar physics community is participating the project as a national member, contributing a full set of instruments and a site. The key instrument is a high resolution spectrograph which, when adopting iodine cell for wave length calibration, can deliver radial velocity measurements at an accuracy of 1 m•s-1. Such a high accuracy together with the long term stability is the keys to the science goals of SONG, one of which is to study the internal structure of stars directly using the technique of Asteroseismology. In this paper, we are going to present the design, parameters and performance of the spectrograph by using spectra taken during the commissioning of the system. As long term thermo-mechanic stability of the system is extremely important for the science goals, we will also describe the laboratory environments to realize such a condition.