Hi Mradula!
If you're aspiring for doing Ph.D. in Psychology program, you need to meet the following minimum eligibility criteria:

• Postgraduate degree in Psychology, completed from a recognized institute/university
• A minimum aggregate score of 55% (50 % for SC/ST candidates) or equivalent grade at the level of post-graduation
• At least 5 years of teaching/ industry/ professional experience at a senior level
• In some cases, M.Phil. in Psychology is also preferred

But for being able to apply for Ph.D. in any university for any course, you must first be a post graduate, without which you will not be eligible to apply for PhD. Any one of the above eligibility criteria, if unfulfilled, will make you ineligible for applying for PhD program in any university.
Good Luck!