I heard that china gonna block bitcoin signal and shut down all the miners. Is it possible? if possible is there any way to bypass it？Will Core release new update to prevent this?
block bitcoin signal
What signalling? Do you mean mining?
Is it possible?
Maybe, for some pools. But it may not be possible for some pools. Here's a tweet from ViaBTC's CEO:
Is there any way to bypass it?
Sure, they can set up VPNs on their US or other countries' servers. But no one will do that. No one wants to go to jail for that.
Will Core release new update to prevent this?
Are you asking, that what is going happen to difficulty? Currently 70% of the hashrate comes from China, if they shut down at the same time, then the block will come every ~ 35 minutes, not 10, making the mempool bigger and transaction fees will go up.
Core can release an emergency update, that is scheduling a hard fork to lower the difficulty.