After graduation is any entrance required for doing llb course for 3 years?

If you have completed your graduation, then you are eligible for giving CLAT PG exams as well.
The eligibility criteria for pursuing LL.B in most of the top universities is that you have to get minimum of 50% marks in your graduation degree and you might have to clear some entrance test with it, (it may vary with the university you want to take admission in)

After LL.b you can appear for Civil and Judicial services in your respective States. IAS Services, JAGS, services in Army, Corporate Lawyer, Legal Advisors in MNCs and Companys, Legal Processing outsourcing, Practice in Criminal, Civil or Income Tax as an Advocate.

I'll point you done about the ENTRANCE EXAM FOR LLB course now...
Entrance exam for 3 year LLB course in DU in conducted in June. Law faculty admits approx 2600 students every year for its 3 centres namely Campus Law Centre, Law Centre-1 and Law Centre-2, all situated in north campus.

Though DU has not specified the syllabus for LLB entrance but by going through previous papers, the pattern is very clear to understand. Generally, questions are asked from English language & comprehension, current affairs & general knowledge, reasoning & analytical ability, basic arithmetic, Indian polity(constitution) and legal aptitude. Legal aptitude consists of some basic legal principles and maxims.

175 questions are asked, having 4 marks for each with negative marking ie 1 mark for each wrong answer. Weightage for these sections is variable but constitution and legal aptitude part is the most important, so you should focus on every segment of the syllabus without leaving any of them. I would suggest to go through previous papers and solve them.

This is the general pattern of the exam. If you have any other query, do not hesitate to ask in comments.

Thank you.