Can the ECDSA still work without present of hashing function?
The truthful answer here is that I don't know. I am pretty sure actually that the better answer is that this is unknown.  The assumption that the hash is only required for collision resistance is blatantly false, since typically one needs a random oracle for such schemes. In ECDSA specifically, we don't have actually have proof of security even with a random oracle, so it's even worse. However, given that it's been around for so many years, its security is essentially a well accepted assumption. However, as soon as you change something, and not hashing the message is certainly changing something, then it falls apart.