Here's a Wall Street Journal article which states China's perspective that revaluing the Chinese yuan would hurt the US economy. The argument is that, while the yuan is undervalued, the US economy is too depending on low costs from China.
Behind the calls for revaluation lies an erroneous assumption — that rectifying the trade imbalance will aid the U.S. economy. In reality, say the authors, the growing Chinese surplus has strongly benefited U.S. companies and consumers. U.S. companies have achieved strong profits by tapping China’s low labor and production costs. They note that more than a quarter of China’s exports are generated by U.S.-owned corporations, who eventually pass on the savings to American consumers. In addition, China’s central bank has been able to buy U.S. debt, further sustaining the U.S. economy.
I've always thought this, but the article states it rather eloquently.