Cheng Yi (程异) (died May 21, 819[1]), courtesy name Shiju (師舉), was a Chinese economist and politician of the Tang dynasty, serving as a chancellor during the reign of Emperor Xianzong.
[2] By the end of Emperor Dezong's Zhenyuan era (785-805), Cheng was serving as an imperial censor with the title Jiancha Yushi (監察御史).
He was then made the official in charge of the directory of salt and iron monopolies and grain supplies' facility at Yangzi (揚子, in modern Yangzhou, Jiangsu).
Around that time, he also became an associate of Wang Shuwen, who was a close associate of then-crown prince Li Song, along with such other junior officials as Wei Zhiyi, Lu Chun (陸淳), Lü Wen (呂溫), Li Jingjian (李景儉), Han Ye (韓曄), Han Tai (韓泰), Chen Jian (陳諫), Liu Zongyuan, Liu Yuxi, and LIn Huai (凌準).
It was said that Cheng spent much his effort in tax reform and was hard working, removing much of the problems that the taxation systems of the Yangtze River-Huai River region was experiencing at the time.
[2] As of 817, when Emperor Xianzong was conducting a campaign against the warlord Wu Yuanji, who controlled Zhangyi Circuit (彰義, headquartered in modern Zhumadian, Henan), Cheng was sent out to the Yangtze-Huai region to seek additional revenue.
In 818, Emperor Xianzong made both Cheng and Huangfu chancellors de facto with the title Tong Zhongshu Menxia Pingzhangshi (同中書門下平章事), and also made Cheng the deputy minister of public works (工部侍郎, Gongbu Shilang), over the strenuous objections of the chancellors Pei Du and Cui Qun.
Still, it was said that Cheng knew that the popular sentiment at the time opposed his ascension, and therefore behaved humbly, and for more than a month did not dare to exercise chancellor authorities.