Before the 2016 PLA Reorganizations began, the PLA structure under the Central Military Commission (中央军事委员会), was based on a General Headquarters (GHQ, 总部) of Four General Departments (四大总部), 7 Military Regions (七大军区), and service (军兵种) organizations. The following chart displays the previous structure, from the CMC down to basic campaign legions (基本战役军团), thus displaying the main strategic and tactical organizations and their relationships.
Note, these charts do not include the Peoples Armed Police (PAP, 中国人民武装警察部队), who prior to 2016 also reported to the CMC as a paramilitary force. In the years immediately preceding the 2016 reforms, it seems the PRC, and thus MND (国防部) and PLA would prefer to leave off the PAP from most PLA references, but acknowledged they had a dual command track, through the Ministry of Public Security (MPS, 公安部) and the Central Military Commission. Since the reforms, the PAP appear to be included as a military force more often. Such as having the PAP Academies listed in the announcement of the reform of military academies, announced in June 2017.