It said the port group needs more time for preparation.
"It's good news since the current market situation in Hong Kong and China is unfavourable," China Merchants Chairman Fu Yuning told reporters on Tuesday.
China Merchants, which commands more than one-third of the China market, paid 847.3 million yuan earlier this year for a 5.4 percent stake in Ningbo Port, the operator of China's eastern port of Ningbo.
Ningbo Port said in March that it was looking to float shares both on the mainland and in Hong Kong this year to raise money for expansion. China Merchants posted a 33 percent rise in first half net profit to HK$2.0 billion.
But traffic growth in many Chinese container ports are seen slowing as the country's exports growth trend continues to soften on weakening global demand.