Webmasters may need to transfer, or copy, the content of one WordPress blog to another. If this happens to be you, then WordPress is equipped with a feature that allows for this to take place seamlessly and almost effortlessly – just another benefit of WordPress.
Content can be the entire blog, posts only, pages only, or contacts forms. The steps are essentially the same, at one point of the process you will need to choose which content to transfer or copy.
In this tutorial we will go over the steps to accomplish the transfer of all the content within a blog to another.
Log in to the dashboard of the source blog then hover your cursor over “Tools” and then click “Export”, as shown by the red arrows below:
In the following page, check “All content” and click “Download Export File”.
Note: Check “Posts”, “Pages” or “Contact Forms” for partial content export.
Save the file to your computer.
Next, you will need to log in to the dashboard of the destination blog, then hover your cursor over “Tools” and then click “Import”.
In the next page, click “WordPress”.
In the following screen, you will prompted to install the WordPress importer, click “Install Now”.
Note: If you’ve already used the importer in an earlier time, WordPress may skip this step.
Then click “Activate Plugin & Run Importer”
Then browse for the file you exported from the source blog, and click “Upload File and Import”.
In the next page, you will need to either create a new user for the posts or assign an existing one. Once you’re done, hit “Submit”.
And that’s it! You have copied content form one blog to another
Source : https://www.greengeeks.com/kb/933/how-to-transfer-your-wordpress-content-from-one-blog-to-another/