Gregorio Manzano's men hit the front five minutes before half-time through Joffre Guerron
Zhang Xizhe, Pablo Batalla and Peter Utaka then added further goals in the second half as Guoan bounced back impressively from a 2-1 defeat to Shanghai Shenxin last time out.
The win moved them to within a point of defending champions Evergrande, who were held 1-1 at home by Guizhou Renhe.
It could have been even worse for the hosts, who fell behind to Chen Zijie's 38th-minute opener, but Mei Fang equalised 12 minutes after the break as Marcello Lippi's men dropped points for only the third time this season.
At the opposite end of the table, Changchun Yatai climbed above Henan Jianye and out of the bottom two with a 2-0 home success over Liaoning Whowin.
Cao Tianbao edged them ahead after quarter of an hour, with Eninho giving the home side a measure of breathing space midway through the second period.
That ended a run of three consecutive defeats for Dragomir Okuka's men, and lifted them two points above Jianye, who went down 2-1 at home to Shenxin.
Jianye fell behind to a strike from Jailton Paraiba midway through the first half, but pulled themselves level with Xu Jang's effort on the hour.
Yang Jiawei came off the bench for Shenxin shortly afterwards and netted the winner six minutes from time.
Elsewhere, Shandong Luneng moved into third, above Guangzhou R&F whom they beat 3-1, while Tianjin Teda won 3-2 at Dalian Aerbin to claim their third consecutive victory.
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