Shen allegedly killed his fellow workers with an iron bar on Saturday at a construction site in the provincial capital Guangzhou, state-run Xinhua news agency reported.
He went on the killing spree after he was taunted by his fellow workers while installing electrical equipment, police said.
Several people were injured in the brawl, five of whom died.
The Southern Metropolis Daily quoted a witness Li Xing as saying that the bar was "close to 80 centimetres in length".
The victims were aged between 40 and 45, and from southwest China's Sichuan Province.