The shields were discovered at Huahaizi (sea of flowers) Lake in the Altai mountains, which borders Mongolia.
The shields are pentagonal stones, one with a circle carved in the centre, surrounded by a herringbone pattern, state-run Xinhua news agency said.
"Initial researches show the shields could date back to the late Bronze Age, roughly 3,000 years ago," said Lyu Enguo, researcher with Xinjiang's archaeological institute.
Experts from the Chinese Academy of Social Sciences, and the cultural relic bureaus of Altay Prefecture and Qinghe County started the excavation in July to find ways of better protecting the relics.
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Badly affected by earthquake and climate change, the stone complex has been eroded by the lake water, and will be further damaged if protective measures are not taken as soon as possible.
Archaeologists have compared the patterns carved on the shield with those on deer stones. Pentagons and herringbone are on many deer stones found on the Eurasian steppe.
There are many theories behind their existence and the people who made them, but expert opinion remains divided.
The patterns at the current site are especially similar to those on deer stones from Mongolia's Khovsgol Province, roughly 2,000 km away to the east, said Lyu.
Experts believe the stone shields were not used for combat, but for sacrifices after they were blessed and dedicated.
"They are most likely to be ritual objects for high-level sacrifices, to drive out evil spirits," said Guo Wu, associate researcher with the Chinese Academy of Social Sciences.