how can i print handrail without any distortion Even Though i decrease the temperature and the speed of machine
the machine is Ultimaker 2 Extended

Cooling fan.

Print horizontally. This would increase the quality and also lower the print time.

Where you have corners in your handrail model, simply split into 2 parts that you print separatelly and horizontally and then assemble / glue into final shape.

Like said before, you print this horizontally.

Always try to optimize the orientation of your print for best quality if possible.

I tried , nothing change same bad quality

Well, ok.

It would be nice if we knew a bit more about the object and the print settings you are using.

If the print is actually very small, I would suggest you try printing 2-3 of them at the same time.

If cooling is our issue, printing multiple objects gives the material more time to cool.