Welcome to the forums, @pravin_nirakar.
There could be many reasons for this. Perhaps your AdWords campaign is not worded well, so that when people arrive on your site, they find it is not what they were expecting and leave again. Perhaps they are reluctant to buy expensive items via an unknown site and prefer to look for a well-established retailer. Do you have all the relevant information such as TOS, trading address etc. readily accessible?
You mention this is an affiliate site. Do you mean that you are simply advertising items on other sites, and picking up a commission when somebody buys via your site, rather than actually selling items yourself? If so, what added value does your site have? What reason would there be for me to choose to shop at your site, rather than go directly to the sellers?