The US's whole financial system is tied into its stock market and the financial sector around it (because of leverage and derivatives and every company being public) -- I understand this may not be the case with China? Or am I wrong on this front.
But, even in the US, I think stock markets are like a balloon tied to the wrist of a toddler on a windy day. They may very generally track where some part of the economy is, but there's too much interference and interpretation to get a precise picture. Even worse, the length of the string is unclear.
The 1987 crash was the largest in US history. In one day, the Dow Jones dropped 22%. Yet, it didn't even cause a recession.