In state-owned enterprises in China, according to their scale and importance, government officials at corresponding levels are usually directly appointed as the chairman. These officials will also be removed from the status of government officials after serving as the chairman of the board of directors.
But people usually give treatment according to the administrative level of officials, and then they become chairmen. For example, central enterprises are usually deputy ministerial level. Provincial enterprises are usually the deputy department level, and municipal enterprises (prefecture-level cities) are usually the department level.
To determine what level an enterprise belongs to, just look at the name in front of the state-owned enterprise. For example, "China" starts with central enterprises, while China Petrochemical and China Mobile are all central enterprises; Provincial enterprises begin with "XX province", such as "XX province transportation investment company", and so on.