Chinese financial markets will close on Thursday and Friday for the Dragon Boat weekend holiday.
The blue-chip CSI300 index fell 0.4 percent, to 3,163.99, while the Shanghai Composite Index lost 0.3 percent, to 2,927.16 points.
U.S. index publisher MSCI will decide on June 14 whether to add Chinese shares to its emerging market index.
Monthly data released on Wednesday showed China's exports fell an annual 4.1 percent in May, more than expected and the 10th decline in the past 12 months.
Imports were more encouraging, however, declining only marginally and much less than expected, pointing to improving domestic demand and adding to views that the economy may be slowly stabilising.
Most stock sectors fell, with materials and consumer shares leading the decline.