China's March exports unexpected fell 2.7 percent from a year earlier, the first drop since February last year, while imports grew 14.4 percent, more than expected, customs data showed on Friday.
That left the country with a rare trade deficit of $4.98 billion for the month, also the first since last February.
Analysts polled by Reuters had expected March shipments from the world's largest exporter to have risen 10.0 percent, slowing sharply from a 44.5 percent spike in the previous month which was believed to be heavily distorted by seasonal factors.
Import growth had been expected to pick up to 10.0 percent, after slowing sharply to 6.3 percent in February.
Analysts expected China would record a trade surplus of $27.21 billion for last month, from February's surplus of $33.75 billion.
For the first quarter, exports rose 14.1 percent, and imports rose 18.9 percent on-year.
China's trade performance has got off to a strong start this year, following through on a solid rebound in 2017, thanks to sustained demand at home and abroad.
But the export outlook is being clouded by an escalating trade dispute with the United States, which could disrupt China's shipments and its supply chains, while a cooling property market may curb China's demand for imported raw materials such as iron ore.
Separately, China's dollar-denominated trade surplus with the United States rose 19.4 percent in the first quarter.
—CNBC contributed to this report.