Abstract: To observe spectral line is one of the key targets for Tianma 65m Radio Telescope. Based on the Digital Backend System (DIBAS)-which was jointly designed by National Radio Astronomical Observatory (NRAO) and Shanghai Astronomical Observatory for pulsar and spectral line observation, we have developed a set of observation control software, hardware as well as software for flux calibration, and we have also designed a frequency calibration program for spectral line observation. Meanwhile, we have tested the observation and data calibration system. Results prove that this system is highly effective. Moreover, this system has been open to domestic observers since the second half of 2015. From then on we have obtained considerable results. The first part of this paper introduces in detail the components and functions of DIBAS; the second part shows the working process of the observation control software; combined with observation data, methods of flux calibration and frequency calibration are discussed in the third part; the last part presents our future plans for this system.