The Long March 3A (), also known as the Chang Zheng 3A, CZ-3A and LM-3A, is a Chinese orbital carrier rocket, part of the Long March family of expendable rockets. A three-stage rocket, it was usually used to place communications satellites and Beidou navigation satellites into geosynchronous transfer orbit. It was manufactured by the Great Wall Industry Corporation.
The Long March 3A is the first variant of the Long March 3. The first stage was lengthened from to , and the third stage was enlarged and redesigned to accommodate two YF-75 rocket engines, whereas its predecessor had a single YF-73; this gave it the capability to lift into geosynchronous orbit, compared to the Long March 3's . A new computer system was also installed.
The first and second stages used hypergolic propellants (unsymmetrical dimethylhydrazine and nitrogen tetroxide), while the third used cryogenic fuel (liquid hydrogen and liquid oxygen).
Its achievements include powering the first two BeiDou navigation satellites into orbit (Beidou 1A on 30 October 2000 and Beidou 1B on 20 December), as well as China's first Moon probe, Chang'e 1, into lunar orbit in 2007.
It formed the basis of the Long March 3B, which by adding four strap-on booster rockets increased the lifting capacity to .
Long March 3A rockets were launched from Launch Areas 2 and 3 at the Xichang Satellite Launch Center (XSLC).