I\'m doing a project using ebay and amazon api.
I\'ve uploaded products to ebay sandbox using the api.
but I searched for api to add products in amazon api.
You have to use the Amazon MWS API (it's not the same as AWS product API) in order to upload your products to Amazon. Here you can read everything you need to know about MWS.
For your particular problem, you'll have to submit a feed which contains the product data you want to upload. Here is the documentation about Amazon's feed mechanism and feed submit operation.
UPDATE:
There are the feed client libraries, with the code samples, for C#, Java and PHP. For example, if you download the Java client library, you'll find a great example within the file on the path: src\com\amazonaws\mws\samples\SubmitFeedSample.java, etc.
If you are using another language, you'll have to write your own code, but the approach should be straightforward: you have a WS end-point (i.e. https://mws.amazonservices.com) and you have to execute the SubmitFeed operation against it.
An XML sample of the feed content
Feed content example.