Most modern devices are dual voltage (meaning they can handle both American and Chinese voltage.) American voltage is comparatively low, whereas Chinese is a bit higher, so if your device is NOT dual voltage, you can fry it pretty easily after just a few seconds of use. Check the power label on your device. If it's a laptop, it's usually on the power cord brick. If it says 100-240V on it, you're OK. If it doesn't say 240V, you'll need an voltage converter. My laptop has no problem. My XBox on the other hand, says 100-127V, so if I plug it up here, I'll fry it in a minute. Voltage converters (not plug adapters, mind!!) can be purchased at Best Buy or Radio Shack for upwards of $50US.
Also, you might need to get a plug adapter, as the plug configurations are different here. about 8 years ago