NTSC's GPSCV comparison system was first set up in 1990 and the BIPM began to publish NTSC GPSCV results from January 1991. Now, daily international time comparison is done mainly by a TTR-6 timing receiver following the BIPM GPS/GLONASS tracking schedule. The comparison data are sent to BIPM every month via the internet. Early this year, two R100/30T combining GLONASS/GPS receivers, which are 12-channel, dual-code, dual-system timing receivers, were built into the UTC(NTSC) time keeping system to enhance the quality of the time link with UTC and other time labs in the world. For the past decades, international time transfer, as used for the computation of TAI, has been carried out using single-channel C/A-code GPS receivers and an international CV schedule of a standard 13-min track. The performance of single-channel GPS and GLONASS CV time transfer techniques is not sufficient for comparing current atomic clocks and must be improved soon. Use of multichannel, dual-code, dual-system (GPS and GLONASS) observation is one of the methods that has been used recently. The first multichannel GPS links were introduced into TAI at the beginning of 2000. The introduction of multichannel GPS + GLONASS links into TAI is also being studied. Procedures for the use of multichannel GLONASS P-code and GLONASS precise ephemerides were established.