Abstract: To get good antenna tracking pointing accuracy under imperfect measurement link status of complicated system, methods and measurements of cubic radiation patterns and cross scanning-and-tracking are proposed for the two 20 m Az-El antennas, which will be updated to take part in the observation and calibration of Mingantu spectral radioheliograph(MUSER), a powerful instrument dedicated for solar radio imaging observation. Least square method is also used to obtain the 8 parameters of the 20 m antenna pointing model. After calibration, the pointing accuracy is improved from about 12' (rms) to about 4.4' (rms), testifying the reliability of the proposed methods and providing a good reference for other complicated telescope systems.