PetroChina, China's biggest oil and gas producer, posted more than double a year earlier in the second quarter to 16.94 billion yuan ($ 2.48 billion).
Net profit for the first half of the year increased 114 percent year-on-year to 27.09 billion yuan, according to a notice sent by the company to the Shanghai Stock Exchange.
The company's best quarterly performance since the second quarter of 2015, according to Reuters data. The gains are due to the oil price recovery since mid-2017.
The results exceeded the company's forecast for July, with earnings of 26.17 to 28.17 billion yuan in the first half.
Revenue for the first six months of the year was 1.109 trillion yuan ($ 162.19 billion).
While PetroChina's crude oil production grew to 437.7 million barrels in the first half of 435.8 million in the first half of 2017.
Gas production in the first half rose 3% year-on-year to 1791 billion cubic feet.
And boosted the performance of the three major Chinese oil companies thanks to strong refining margins, high oil prices and strong gas sales.