Hi Feifei, your question was interesting since I also read Chinese on my ebook reader, the Cybook Gen 3. However, since I also read in several European languages too, I found the dictionaries included on the Sony PRS-650 a big plus and bought one.
After reading your question, I went to the Shucang site and downloaded several Chinese ebooks in ePub format. I loaded them on the Sony reader and I am sorry to say that though they appear in the library page, they do not display the text at all except as little squares.
I am very satisfied with the way my Cybook displays Chinese texts in the MobiPocket format but it is getting a bit old now. I am looking to getting a BeBook Neo since it will also reads MobiPocket files and seems to handle pdf files better than other readers.
Maybe if you bought a Sony PRS-650 in China or Hong Kong, it might display Chinese. By the way, does you wife read Chinese in the simplified script or the classical script?