Kuzya, a Siberian tiger released into the wild by Russian President Vladimir Putin in May, is the second suspected to have roamed into China.
The tiger was spotted in China in October, authorities confirmed on Thursday.
Another tiger, Ustin, was released in June.
According to Jiang Guangshun, executive vice director of the Feline Research Center under the State Forestry Administration (SFA), Russia had said it thought Ustin might have entered China. The tiger's tracking device showed it to be on Heixiazi Island in Fuyuan county in northeast China's Heilongjiang Province.
It had roamed six kilometers past the national border, Jiang said.
Experts from SFA are heading for the island, which is shared between China and Russia as a key cooperation zone by the two countries.
About two years ago, Russian experts rescued five tiger cubs. Putin freed three of the tigers in May.
The tigers were released with satellite-tracking collars.
Kuzya has been detected at the Taipinggou nature reserve in Luobei County of Heilongjiang, and was found moving further away from Russia. Chinese experts believed that it might spend winter in China.