On the afternoon of September 25, all participants of the "Tiangong-1" mission completed a joint rehearsal at the launching site. The results showed that the launch conditions were ripe with smooth commanding within all systems and units, proper technical conditions and devices in sound operation.

The combined launcher-rocket of the "Tiangong-1" target spacecraft was transported to the launching site on the morning of September 20, and then function test was conducted on the launcher and the target spacecraft in addition to interface matching check, joint check upon locations of the launcher and the rocket, joint drill, and electromagnetic compatibility testing. The comprehensive joint rehearsal at the launching site conducted on September 25 was a comprehensive simulation drill according to the launching procedures which verified the working status of major systems.

At 14:30, the joint rehearsal entered the 3-hour countdown under the unified command of the Beijing Aerospace Control Center. The "Tiangong-1" target spacecraft will receive comprehensive quality review on all of its systems and complete fuel filling in the next few days.