"Then my total income is 10000 + 20000 = 30000 which should be in Box-1, but today Box-1 is just 10000."
If this is a genuine "vested RSU" situation then that doesn't make sense.
Instead of RSUs did you get a grant of Restricted Stock (RS) and make an 83(b) election at the time of the grant? This still wouldn't make a huge amount of sense as the vesting of the restricted stock wouldn't be a taxable event, an event requiring withholding, but it could, sort, kinda, explain the W-2 presentation (though I'm not at all sure that presentation is actually correct if that's the case.)
