China's commercial real estate sector remains healthy but there is a risk of oversupply in office space, a report from real estate institute Insite showed on Wednesday.

An expected 15 million square meters of new supply will enter China's major 20 cities monitored by Insite in 2014. By the end of 2016, the new supply will balloon to 35 million sq m, 54 percent of the existing stock in 2013, according to the report. The new supply of office space will reach 58 million sq m, 173 percent of the existing stock.

"Though the commercial real estate sector is growing a little fast, it is healthier than the office sector," said Sunny Zhang, general manager of the corporate research center of Insite.

"A lack of differentiation of shopping malls is one of the major risks for the commercial real estate."