Can I measure 220 V AC signal by spectrum analyzer ?
I want to observe noise in mains voltage.


And


  My spectrum analyzer GSP-830.


The lowest frequency that the GSP-830 can measure is 9 kHz so, from your limited details I would say it may not be suitable because it will not be able to measure the first 150 harmonics.

The device also has a limited input amplitude range: -


  Overload Protection   Max. +30dBm, ±25VDC


It's also got an input impedance of 50 ohms.

If you still wish to proceed then more details are required but, it is highly likely that some form of isolation barrier will be needed to prevent electrocution or destroying the GSP-830.