By the time Lin moved in for his first lift in the finals, it was clear he could win the title with only a routine performance and he put on one that was better than that.
His total of 344 kilograms was 11 more than that lifted by Triyanto Triyanto of Indonesia.
The bronze went to Razvan Constantin Martin of Romania.
China won eight of the 15 weightlifting gold medals awarded in Beijing four years ago, but the Chinese have been challenged at these Games by both North Korea and Kazakhstan.
Those countries have won two gold medals each with Kazakhstan getting one Tuesday from Maiya Maneza in the women's 63-kilogram class.
Svetlana Tsarukaeva of Russia finished second to Maneza and Christine Girard of Canada was third.
Kazakhstan has won three gold medals overall in London, including one in road race cycling, after winning two during the entire 2008 Olympics.