The ring abducted babies in Yunnan and sold them in Hebei and Shandong provinces in northern China, according to the bureau.
Railway police in Yunnan's provincial capital of Kunming have arrested 76 suspects so far after traveling to seven different cities in the three provinces since November 2011 to bust the ring.
The ring purchased the infants at a price of 8,000 to 10,000 yuan ($1,266 to $1,582) each in Yunnan and sold them in Hebei and Shandong for 20,000 to 50,000 yuan, according to the bureau.
The family-based ring is connected by well-organized members who are responsible for abducting, purchasing, transporting, introducing and adopting infants, said Wang Ansi, an official with the public security bureau of the Kunming Railway.
The ring could achieve one trans-provincial trade in three days to traffic the infants, who were stolen from the Zhuang-Miao autonomous prefecture of Wenshan in Yunnan province, he said.