"He was a long-term overwork, eventually fell at work, at April 23, 2014, morning, sudden death, aged 48 years," the commission said in a statement (as translated by Google and confirmed by Bloomberg). He had been working all night to get a report done.
Google's translation of the CBRC statement isn't great but you can get the gist: "To learn from Comrade Li Jianhua, as he does, always firm ideals and beliefs, this situation, loyal to the cause of the Party and the people, unremitting struggle, sacrifice everything. ... To enhance the quality of work, Comrade Li Jianhua long overtime, night and day, all the energy and passion into the regulatory business."
The statement basically suggests that all Chinese can "learn from his selfless work." Here's the context, from Bloomberg:
About 600,000 Chinese a year die from working too hard, according to the China Youth Daily. China Radio International in April reported a toll of 1,600 every day.
... Employees in Li's department regularly worked until midnight or later, according to a colleague who asked not to be identified because he's not authorized to speak publicly. His death, categorized as from "long-term overwork" by the CBRC, was the latest in a string of cases garnering media attention.
Ogilvy PR's China unit last year denied that one of its workers was killed by the overtime he had worked in the prior month (he had actually been sick, the agency said). Asians even have a word for death-by-overtime: "guolaosi" in Chinese and "karoshi" in Japanese.
It's not just an Asian phenom, of course. Last year, a 21-year-old Bank of America intern died in London after working long hours.
Li apparently had an attack of shingles - which is sometimes related to stress - in the days before he died but did not go to the doctor because "he didn't have any time," Bloomberg says.