I bought an ag06 i test it its normal but when i turn up the gain or turning on the amp simulator i start to hear noise is my ag06 faulty?
I guess you’re talking about the Yamaha AG06 mixer.
I have one too, and love it for what it is, i.e. a well-built low-cost compact mixer.
It’s better suited for live applications than for studio quality recordings.
It’s normal to hear “noise” on any mixer at any price point, and certainly not surprising on an entry model like the AG06, and especially when using special effects like amp simulation.
Noise is a somewhat subjective concept.
If you’re recording/playing music with it at a ‘normal’ level, the ‘noise’ should not be (excessively) distracting.
If noise is too distracting, then it could be defective, but more likely, you’re pushing it beyond its limits with your setup. If, for ex., you have to push the Gain knobs to the max, then your source might be inadequate in this context - try with a microphone with higher gain (ex. with phantom).
And in a guitar amp simulation… noise is sometimes not only expected, but desired! 
Does the hiss noise get into the recordings? Also is it supposed to be that loud?
The hiss from the mic+preamp of the ag06 will be recorded, not the noise from the output stages (headphones or line out, etc.)
When you say “loud”, it is very subjective.
If you turn the gain knobs to the max, it is “loud” and not usable to my opinion, but that will be the case with about any live console, and even most “studio-quality” $$$ preamps.
But these knobs are not meant to be used “full throttle”.
Normally, if you need more then about 80% gain, then it’s your source that is not appropriate for the application.
Do you have access to a mic with phantom power to make a test? (What model?)
If you still have problematic hiss/noise at normal listening levels, then your ag06 might have an issue.
Otherwise, please describe exactly how you make that test that you find too noisy.