On arming my quadx all the 4 motors are not spinning with same speed and on on increasing throttle also the motors are spinning at different.

Looks like you need to do an ESC calibration.

Bro i have already done esc calibration, one by one esc by the transmitter

Okay, try doing it together with the board

Try this

That's common with multiwii but it will fly once you start flying.

When you try to hover then multiwii will give out correct outputs to ESC.

And also don't try calibrate ESCs individually. Calibrate all at once either by using a parallel board PCB/veroboard or something similar.