beat knock on exhaust when I accelerate

Beat knock on exhaust... Can you explain?

Its like is busting,and it doesn't have power ,when I acceralate it smoking... Alot

Where is the smoke coming from, what color is it, have you checked the catalytic converter to make sure it isn't loose inside?

Its coming from exhaust.. Its always smoking Blue

Its Blue... And its always smoking and its burning the fourth plugs.

If it is blue, then oil is burning. Listen, if this is the original engine / miles, chances are the #4 cylinder is low on compression due to an issue with rings. As a result, burning oil and fouling the plug and causing a misfire and power loss. Chances are that the oil burning has damaged the catalytic converter. If the mileage is correct, I recommend checking engine compression.

Eish!! But my mechenic isi suspecting pistons bearings rings.. So if I may ask what is needed to be repair ???

Before anything is done, you should check engine compression to confirm that is the problem. As far as your mechanic, I think you are a little confused. Most likely, he said to replace piston rings and while they are out, replace connecting rod bearing and main bearing in the engine.

OK this can stop my car smoking?

checking engine compression won't stop the problem. It will determine if you need piston rings. Replacing rings and bearings is an expensive job, and I just want to know if that needs done before you spend that kind of money.