Denisov said he used to work in Beijing in the late 1970s as China began its reform and opening-up, and there has been "tremendous progress" since then.
Noting that he will attend a series of events celebrating the 70th anniversary of the PRC, the Russian ambassador said he is sure China will enjoy greater progress.
Eoin O'Leary, the Irish ambassador to China, said he welcomes the fact that China is opening up to the world.
Mentioning China's economic growth and the efforts it has made to tackle poverty, O'Leary said: "I think it's hard not to be optimistic about China's future when you see the progress that's been made so far."