I have website wherein backlinks are increasing but Google SERP is down. Please tell me how it’s possible.

Dear friend,
You should try to get backlinks through high PR forums. Hope it will be help you.

make sure back links are 'dofollow' and contribute in relevant forums and blogs. create unique and relevant content. you may also want to consider article marketing.

If the backlinks for your site is increasing and the ranking is not increasing then maybe it is because some of your backlinks are broken

I personally believes that the backlinks you have generated is quantity and not in quality.Well Google gives more preference to the quality as compare to the quantity..