PetroChina was established as a joint stock company with limited liabilities under the Company Law of the People's Republic of China (the PRC) on 5 November 1999, as part of the restructuring of CNPC. In the restructuring, CNPC injected into PetroChina most of the assets and liabilities of CNPC relating to its exploration and production, refining and marketing, chemicals and natural gas businesses.

PetroChina Co. Ltd. engages in the petroleum related products, services and activities. It operates through the following business segments: exploration and production; refining and chemicals; marketing; natural gas and pipeline; and head office and other.

The exploration and production segment involves exploration, development, production, and marketing of crude oil and natural gas. The refining and chemicals segment focuses on the refining of crude oil and petroleum products, production and marketing of primary petrochemical products, derivative petrochemical products, and other chemical products. The marketing segment includes marketing of refined products and the trading business. The natural gas and pipeline segment comprises transmission of natural gas, crude oil, and refined products and the sale of natural gas. The head office and other segment relates to cash management and financing activities, the corporate center, research and development, and other business services supporting the operating business segments of the group.

Traded in Hong Kong and New York, the mainland enterprise announced its plans to issue stock in Shanghai in November 2007, and subsequently entered the constituent of SSE 50 Index.

In the 2022 Forbes Global 2000, PetroChina was ranked as the 21st-largest public company in the world.

According to Wikipedia; Forbes