Dr. Lu Rusen of MIT HAYSTACK OBSERVATORY visited XAO in 7th, July, 2011. Dr. Lu has a wealth of practical experience in millimeter wave, millimeter wave VLBI observation and data procession, and has committed to observing and researching high frequency VLBI of compact radio source, especially achieved many important results of multi-band VLBI observation and research in Galactic center. Galaxy cosmology group has communicated with Dr. Lu about researching of frequency VLBI and some difficulties in data processing. Both has reached further cooperation through this visit.