The yuan has weakened 1.4 percent in 2014

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The yuan has weakened 1.4 percent in 2014, the second-worst performing currency in Asia, according to data compiled by Bloomberg. The People’s Bank of China lowered the daily reference rate by 0.18 percent to 6.1312 per dollar today, the weakest level since Dec. 3.
The drop in exports highlights the challenges for Premier Li Keqiang in achieving this year’s economic-growth target of 7.5 percent. Li announced the goal last week at the opening of the annual meeting of the National People’s Congress in Beijing, a pace unchanged from last year.
It won’t be easy for China to achieve 7.5 percent this year and policies may be introduced to stabilize growth in the second quarter, the China Securities Journal said in a commentary.
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China Stock-Index Futures Slump as Exports Drop Most Since 2009

It is quite common for nations to allow their currencies to decrease in value in order to bolster exports to up their GDP especially when exports are dropping like this.