[10][11] The Long March 5 roughly matches the capabilities of American NSSL heavy-lift launch vehicles such as the Delta IV Heavy.

[14] China's main objective for initiating the new CZ-5 program in 2007 was in anticipation of its future requirement for larger LEO and GTO payload capacities during the next 20–30 years period.

Formal approval of the Long March 5 program occurred in 2007 following two decades of feasibility studies when funding was finally granted by the Chinese government.

[19] The launch was planned to take place at around 10:00 UTC on 3 November 2016, but several issues, involving an oxygen vent and chilling of the engines, were detected during the preparation, causing a delay of nearly three hours.

[22][23] Investigations revealed the source of the second flight's failure to be located in one of the core stage's YF-77 engines (specifically, in the oxidizer's turbo-pump).

CASC declared the mission a success within an hour of launch, after the Shijian-20 communications satellite was placed in geostationary transfer orbit, thus marking the Long March 5 program's return to flight.

This variant is used to launch heavy low Earth orbit payloads such as components of the Tiangong space station.

[24] The first flight of the 5B variant ("Y1 mission") carried an uncrewed prototype of China's future deep space crewed spacecraft, and, as a secondary payload, the Flexible Inflatable Cargo Re-entry Vehicle.

[27] Nevertheless, the return capsule of the prototype next-generation crewed spacecraft, the flight's primary payload, successfully landed in north China's Inner Mongolia Autonomous Region at 05:49 UTC, on 8 May 2020.

The prototype spacecraft flew in orbit for two days and 19 hours and carried out a series of successful experiments and technological verifications.

[28] The Y1 mission's core stage may have been the most massive object to make an uncontrolled re-entry since the Soviet Union's Salyut 7 space station in 1991 and the United States' Skylab in 1979, excluding the failed controlled reentry of Space Shuttle Columbia over populated areas of the Continental United States in 2003.

[32] The chief designer of CZ-5 is Li Dong (Chinese: 李东) of the China Academy of Launch Vehicle Technology (CALT).

[42] Potential solutions include restarting engines during re-entry to reduce speed and collision probability, as the case for Long March 2D.

[44][45] Although the probability of rocket debris hitting populated areas is mathematically minuscule, some scientists fear the lax attitude of many countries could eventually result in casualties.

Xu Yansong, former director for international cooperation at the China National Space Administration (CNSA), told the audience on the CNSA live stream for 5B-Y3 that the re-entry process was improved with the "passivation process" (Chinese: 钝化处理[47]), and the core stage was specially designed with lighter materials so the vast majority of components will be ablated during the re-entry.