Hello,
i need to know the datasheet of SMD transistor (6BW) or it's part number.

 

Maybe, or maybe not?
https://www.aliexpress.com/item/SMD-transistor-BC817-25-SOT-23-marking-genuine-6BW/32682725287.html

 

Is there a manufacturer marking on the chip? Like Texas Instruments or something else? Usually when there's insufficient room to mark a chip they put something like that on it. If you know the manufacturer you should be able to figure out what the part is based on its marking. I know as an inspector I've done that plenty of times, but from the other side of the coin. I'd have an in-house part number that would tell me what it was - for instance a 2n2222 transistor. Too small to mark it as such so they would put a code on it. I'd have to go to the manufacturers website and put the 2n2222 in it and research for the size component I had. And I'm just using the 2n2222 as an example. It might come back with the marking being 6BZ or whatever - - - .