But is bigger necessarily better? Experts say the rank in size of China's economy, doesn't mean it's the second strongest.

According to figures released by the IMF, China's GDP per capita totals less than 4300 US dollars, lower than the global average. Chinese officials have admitted China's energy consumption per GDP unit is still relatively higher, and there is also need for structural improvement in the economy.

Analysts also say China's move up the ranks is partly due to Japan's falling exports. That's affected its economic recovery.