"We expect them to finish their work in the next few days. After that, there will be a proposal by NATO's military authorities to the North Atlantic Council," the official told Xinhua on customary condition of anonymity.
The official said that the site-survey would not take weeks, but only days.
The military experts are coming from nations that have shown their intention to provide missiles, as well as from NATO and Turkey, he said.
The Unites States, Germany and the Netherlands have the advanced PAC-3 model Patriot missile that Turkey has requested last week to deploy because of its rising fears of spillover from the conflicts in neighboring Syria.
In response, NATO Secretary General Anders Fogh Rasmussen said that NATO would consider the request "without delay" and would make a formal decision "within days."
Meanwhile, Russia has voiced opposition to the plan and warned Ankara not to increase its military presence on the border with Syria.
NATO foreign ministers are likely to discuss the deployment of the Patriots when they convene in Brussels next Tuesday and Wednesday.