"China won't fall for Cameron's 'sincerity'," the headline of the sharply-written editorial in the Global Times newspaper said, after Beijing was outraged by Cameron's meeting with the Dalai Lama last year.
The meeting had led to a diplomatic deep-freeze between the two nations.
But yesterday the British prime minister met Chinese Premier Li Keqiang in Beijing where he signed a series of trade deals, before holding talks with President Xi Jinping.
"A successful day in Shanghai promoting British exports," the prime minister tweeted. He was attending a business lunch and a "face to face" event at the city's Jiaotong University.
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Cameron has taken more than 100 businesspeople with him to China, including the heads of Jaguar Land Rover, Rolls Royce and Royal Dutch Shell and the chief executive of the London Stock Exchange.
He has kept human rights firmly on the sidelines during his time in China, but the Global Times said his three-day visit "can hardly be the end of the conflict between China and the UK".
China denounces the Dalai Lama- who says he only wants greater autonomy for Tibetans- as a dangerous separatist.
"The Chinese government will surely show courtesy to Cameron. But the public does not forget his stance on certain issues," the paper added.
The editorial also criticised what it called London's interference in the "transition process" of Hong Kong, a British colony before its reversion to China in 1997. It is due to adopt universal suffrage to choose its chief executive in four years' time.
"The Cameron administration should acknowledge that the UK is not a big power in the eyes of the Chinese," it added.
"It is just an old European country apt for travel and study." The Global Times has close ties to the ruling Communist Party and often takes a nationalist stance.
A more conciliatory editorial appeared in the China Daily, which said Cameron's visit would help "pave the way for bilateral ties to flourish".
Meanwhile Cameron's account on Weibo, a Chinese version of Twitter, had attracted more than 200,000 people since it was launched last Friday.