In class 12 I got 73 percent and in JEE main I got 20k rank. Can I get admission to nit ?

No. 75% is compulsory to get admission in NIT's

Hello,
If your board is CBSE and if you are a student of general category, then i am very sorry to inform you that you are not eligible for admission in NITs or IIITs or IITs as you don't have aggregate 75% in class 12th.
But if you are not a CBSE student then check your board's top 20 percentile list to know your eligibility.
And if you are a SC or ST category student, then you are eligible to get admission in NITs or IIITs based on your jee mains rank.
Good luck.

Dear student you have low chance to get admission in nit because your rank is high as compare to nit seat and again I tell you you have few chance wait for that.
Thank you.