A local court said the defendants - mainly health professionals - had used the internet to match buyers and sellers, Xinhua news agency said.
Among them were two doctors, a nurse and an anaesthetist who the court said carried out secret transplant surgery.
A shortage of donors has led to a booming black market for organs.
China's black market for organ donations
The Lixia district court in Jinan city in China's Shandong province said patients were asked to pay at least $57,000 (400,000 yuan).
For many years, China harvested the organs of executed prisoners to help meet demand.
But following international condemnation, Beijing says it ended the practice at the start of 2015.
The government has had some success in registering new legal donors, but there are still many people waiting for transplants.
The country's donor rates are among the lowest in the world - 0.6 donations per million people compared with 37 per million in Spain.
Many Chinese believe the body is sacred and should be buried intact in a show of respect to their ancestors.
Trading in human organs has been banned in China since 2007.
Sixteen people in China have been jailed for up to five years each for involvement in illegal kidney transplants, state media report.