The team arrived in Damascus, bringing to about 60 the number of people on the joint team, Xinhua reported citing an OPCW statement.
It said the advance team had made "good progress" in verifying the information submitted by the Syrian government on its chemical weapon programme.
"At the end of the first 10 days of operations on the ground, the verification teams have inspected three sites and plans are underway for further site visits," the statement added.
It said the team had also overseen the destruction by Syria of some of its munition stockpile as well as some of its chemical weapon production equipment.
The first group of chemical experts started their ground work Oct 6.
The United Nations Security Council said the OPCW will help Syria destroy its chemical weapons by mid-2014. The mission will be expanded as more investigators will arrive in the unrest-torn country by Nov 1.