Although ACAC refers to the ARJ21 as "designed by Chinese with completely independent intellectual property rights", it is being built using tooling which was originally provided by the McDonnell Douglas company for licence-production of the MD-90 in China. Consequently, it bears a strong resemblance to the DC-9 series of aircraft, with an identical cabin cross section, nose profile and tail. The general designer of the aircraft was Mr. Wu Guanghui (吴光辉), and the deputy general designer was Mr. Zhou Jisheng (周济生), with the general engineer was Ms. Jiang Liping (姜丽萍, 1968- ). An all-new supercritical wing, which will have a sweepback of 25 degrees and be fitted with winglets to improve aerodynamic performance, has been designed by Ukraine’s Antonov.[7][8][9] Antonov Design Bureau also assisted project with geometrical determination and integral analysis of the construction strength of ARJ21.[7]

In addition to the baseline and the stretched passenger models, ACAC has also proposed extended-range, freight, and business jet variants.