if my personal website pr is 3 and i acquire back-link from the directory site its pr is 2 or below ,is beneficial for me or not..
Backlinks are always beneficial to PR: the algorithm basically sends you link-juice no matter where you get it from. PR does not measure anything except how many links you have and how "strong" they are. On the other hand, you may negatively affect your SERP if the links are completely irrelevant or otherwise stupid.
Keep in mind that page rank is just one of many factors effecting your websites position and the page rank from the directory must be from the submission page not the directories main page.
Hi, Why are you going for reciprocal directory submission? If you need to go for reciprocal directory submission,then search for directories related with your field. Getting links from them will be more beneficial than opting for general ones.