China’s online population, the largest in the world, is now more than the entire population of the United States, touching 338 million by the end of June after a surge of 40 million in the first six months of 2009. China had 338 million internet users by the end of June, up 40 million from the end of last year, according to the state-run Xinhua news agency, which cited a report by the China Internet Network Information Center.