Genenerate address offline, but blockchain knows about my address I generate new address in client. I hear that blockchain doesn't know about it. Blockchain will know about it when I use this address for transaction.

My example:
I generate this address(offline): 1J1JqUPqKq4XvrDRioMSMYKrwL3wKdJ1Fe
I haven't used yet. How does website blockchain.info know about my address??? https://blockchain.info/address/1J1JqUPqKq4XvrDRioMSMYKrwL3wKdJ1Fe
It only knows anything about the address because you asked about it.

Since the address has never appeared in the blockchain, all it knows is what can be seen from the address: its hash160 value. This is the hexadecimal version of what is encoded in your address, which is a hash of your public key via the algorithm explained here.