There is a pattern to Chinese army (PLA) combat organization. There always was a pattern, but it has changed over time. Historically, the PLA was triangular (three platoons make up a company, three companies a battalion and so on). But during the Cold War era, the PLA evolved into a more complicated organization. In the 1950s, China began to adopt the somewhat different Soviet organization. This meant that a tank division had three tank regiments and a mechanized infantry regiment. The mechanized infantry division was the reverse. Further, inside the regiments, there was a similar square organization: three tank battalions, plus one mechanized infantry battalion in a tank regiment or three mechanized infantry battalions and one tank battalions in a mechanized infantry regiment. Division artillery would typically be as much as six battalions - four of gun howitzers (Self Propelled in tank and mech units) and two of rocket launchers. Divisions also had a light armored recon battalion, with amphibious light tanks and APCs.
The non-mechanized infantry was similar. There were three infantry regiments (originally walking motorized in the 1960s and 70s), and one "tank" regiment. But this tank regiment was not like that of the tank or mech divison. It had only one tank battalion (enough to give each regiment a company), an Self Propelled artillery battalion, and a light motorized recon battalion (jeeps and motorcycles). The division artillery would have towed guns - three or four battalions plus one battalion of rocket launchers.
Fist (assault) units typically had four, and occasionally five or six combat commands (regiments).
Today the organization is more complex, and the formations are shrinking in size. Many divisions have been turned into brigades. The rest were shrunk to just three regiments. But brigades can have as many as six combat battalions. Infantry regiments can be "reformed" and have organic tank units (apparently companies). There are now two tiers of heavy units - those with tracks and those with wheeled APCs. Everything else is motorized (trucks). Typically a division has two different kinds of regiments (mechanized infantry or tanks), although the 10th Armored Division has one regiment with three different types battalions. Tank divisions have also been renamed as Armored divisions. For whatever reason, PLA units seem to be organized on the principle that standardized organization is no longer all that important.
Many divisions were turned into reserve units, Peoples Armed Police Divisions, training schools, or specialized units. For example, there is a Specialized Landing Brigade - sort of assault engineers and assault boat drivers that attach to a division to help it with a difficult amphibious assault. The PLA appears to be getting overspecialized, with too many types of units in tiny numbers (one or two). It may be this means the PLA isn't sure what will work and wants to experiment with lots of options. -- Sid Trevethan