Please go through below points -
Candidates have to complete their 10+2 Examination with Mathematics and English as compulsory subjects & secure at least 50% marks in the examination.
Those candidates have 10+3 year Diploma in any stream, they can also apply for B.Arch programme.
Candidates can get admission in this programme through JEE Main, NATA.
Some private universities also conduct their own entrance test for admission in B.Arch such as BITSAT, SRMEEE, etc.
After completing your B.Arch course, you have a scope of higher study. You can apply for CEED, GATE.

Top B.Arch Colleges in India:

Indian Institute of Technology, Mumbai
Indian Institute of Technology, Delhi
National Institute of Technology or NITs
Punjab University, Chandigarh
School of Planning & Architecture, New Delhi
Government College of Architecture, Lucknow
Government Engineering College, Trichur (School of Architecture)
Government College of Architecture & Sculpture, Mamallapuram

Hope this helps!!!
Good Luck!!!