Liu Weidong was the hero for Changchun, his 76th-minute strike securing a crucial 1-0 victory over Liaoning Whowin.
Qingdao's defeat to Beijing Guoan by the same scoreline saw them finish second from bottom.
Dragan Okuka's men finished one point above Qingdao but their superior goal difference afforded them a degree of comfort.
Elkeson's double took his tally for the CSL season to 24, while Dario Conca also netted a brace and Gao Lin completed the rout.
Manager Marcello Lippi will now turn his attentions to the second leg of the AFC Champions League final, which sees Seoul visit Tianhe Stadium on November 9 following last Saturday's 2-2 draw in South Korea.
Tianjin Teda, the only side to beat Guangzhou, lost 2-1 at Shanghai Shenxin, while Nabil Baha's goal gave Dalian Aerbin a 1-0 victory over Hangzhou.
Guangzhou R&F shrugged off Lu Lin's dismissal to defeat Shanghai Shenhua 4-2.
