Ten women were sold by the gang based in Shandong province over two years, with the buyers paying up to 100,000 yuan (USD 1,660) for each "bride", Hong Kong-based South China Morning Post reported.
The women were bought from their families in Guangdong province and Guangxi region of south China for 3,000 to 5,000 yuan with a promise that they would be married to well-off families, the report said citing official Chinese media.
One suspect in Shandong, identified only by his surname Sun, would find prospective buyers for the women, mainly men from a poor mountainous area of the province.
He would then alert a middleman who would ask local "matchmakers" to find mentally-impaired women in Guangxi and Guangdong.
"People have little awareness of the law. Not many know that such acts are illegal, not to mention telling the police. The women were usually aged between 20 and 30 years old, the report said.
The buyers knew the women were mentally-impaired and only wanted to marry them to have children, Sun said.
"Once you mention a girl would be married into a good family, their parents don't ask too many questions," a middleman surnamed Lan told the police.
Mentally disabled girls are considered a burden by their families, Lan said.
Many of the women were also unable to protect themselves and were particularly vulnerable, the report said.
The girl's families were generally indifferent about the fate of their daughters, according to the report. Chinese families, particularly in rural areas, traditionally favour sons. This has led to the most serious gender imbalance in the world, China's health authorities said earlier this year.
Some pregnant women abort female foetuses and abandon baby daughters because they want to have a son. About 118 boys are born for every 100 girls in China, against a global average of 103 to 107.
