Chinese demand has driven a decade-long spike in elephant poaching in Africa, where the population has fallen.
At its peak in 2014 wholesale prices for raw ivory stood at $2,100 (1,900 euros) per kilogramme in Chinese markets, but by 2017 the price had fallen to $730 per kilogramme, according to the report by two ivory trade experts, Lucy Vigne and Esmond Martin.
"Findings from 2015 and 2016 in China have shown that the legal ivory trade especially has been severely diminished," Vigne said in a statement.
Chinese demand has driven a decade-long spike in elephant poaching in Africa, where the population has fallen by 110,000 over the last 10 years to just 415,000, according to a recent continental survey.
Vigne said both the amount of ivory for sale as well as prices had fallen at 130 licensed outlets in China, reflecting a drop in demand in the world's biggest ivory market.
The researchers said China's economic slowdown, plus a crackdown on corruption which sharply reduced the giving of ivory trinkets as gifts to officials, had also crimped demand.
At the end of this month China's 34 remaining licensed ivory-carving factories will be closed, after a recent government order putting an end to the legal trade.
But it remains unclear how the closing of the legal market will affect the illegal trade in elephant ivory.
International trade in ivory was banned in 1989, yet poaching continued and has accelerated in recent years, feeding a black market controlled by criminal gangs.
Iain Douglas-Hamilton, Save the Elephant's founder, said it was a critical but hopeful moment for the future of elephants.
"With the end of the legal ivory trade in China, the survival chances for elephants have distinctly improved," Douglas-Hamilton said.
"There is still a long way to go to end the excessive killing of elephants for ivory, but there is now greater hope for the species."