Moving to NZ permanently

1) Understand that 160 points is required for EOI.
2) How to get the points in Area of absolute skills shortage? am confused. Any links or references?

Is there any other way to move to NZ first and apply PR?

1-  Yes.
2-  Present your qualification and working experience in the similar field to claim points. work references, training and similar experience would help.

You may obtain a visit visa but that wouldn't help in PR application.

Claiming the obsolete skills points

It's Absolute, not obsolete. 

under graduation  3 years course in bachelor of science

A 3-year undergraduate course is generally not considered as a technical degree (To the best of my knowledge). You can probably do a self-test assessment of yourself via INZ web portal and could check yourself to how many points you can claim. It is really easy as a self-assessment option is available online.

But I never used absolute skills shortage option. If I will use that one I will get 15 points more. But I am confused , what basics it will consider by immigration officer?

Case officer can best answer this. My suggestion is that you may claim the points and take the risk. The case officer generally gives a chance to prove the points. If you're able to do so, you may be lucky enough.