PetroChina Company, Limite (simplified Chinese: 中国石油天然气股份有限公司, traditional Chinese: 中國石油天然氣股份有限公司) (SEHK: 0857, SSE: 601857, NYSE: PTR) is a Chinese oil company and is the listed arm of state-owned China National Petroleum Corporation (CNPC), mainland China's biggest producer of oil.