China are unbeaten in their last three games, following the sacking of Jose Antonio Camacho in June.
The hosts made a flying start and were 4-1 up at half-time in Tianjin thanks to a Yu Dabao double, a Xizhe Zhang penalty and a further goal from Sun Ke.
Shahfiq Ghani had equalised for Singapore after 17 minutes but never looked like threatening, with Long Zheng adding a brace in the second half.
Yu got China off to the best possible start after just nine minutes, finishing off a simple move to put the hosts ahead.
Ke controlled a long ball over the top well before putting the opportunity on a plate for the striker who made no mistake.
Just 10 minutes later, Singapore were level after careless play at the back between captain Zheng Zhi and goalkeeper Yang Hao.
The powerful backpass caused Hao to miscontrol, allowing Ghani in to level matters.
However, Yu was on hand to put China ahead again just past the half-hour mark, with the Dalian Aerbin striker curling an effort past Hassan Sunny in the visitors' goal.
The home side then struck twice in three minutes before the break, going 3-1 up through a Zhang penalty after Wu Lei was fouled by Safuwan Baharudin in the box.
Ke made it four on the stroke of half-time, tapping a Zhang cross into an empty net.
China had to wait until 25 minutes into the second half before scoring again, with Zheng getting on the scoresheet before the 25-year-old completed his double five minutes from time.
