Guangzhou Metro Corp is in talks with Hong Kong-listed property developers to sell the remaining four sites above its Metro Line One.
Vice-manager Wang Wenbin said the sale of the sites had been hit by China's sluggish property market.
It had sold 20 of 24 land lots above the metro line, running from Guangzhou East Railway Station to Fangcun Depot in the southwest, mostly to Hong Kong developers, for 2.1 billion yuan (about HK$1.95 billion).
The company initially expected to make 3.8 billion yuan by selling the 24 sites. It faces a shortfall of 1.7 billion yuan.
Mr Wang said this would be made up temporarily by the municipal government's income from other property sales.
He said Guangzhou Metro Corp was negotiating with various parties, including some listed property companies in Hong Kong, to buy the remaining lots.
He refused to identify the buyers, but noted that it would not cut land prices to lure foreign investment.