The search engine ranking of your web page should not be affected if you switch from one hosting provider to another.
The switch, however, will require you to change your domain’s nameservers and the resulting DNS propagation may affect search engine bots slightly. To avoid that, make sure your website on the previous server has not been taken down for at least 48 hours while the DNS propagation is resolving. And you can easily check in your access logs on the new server or in Google’s Webmaster Tools whether the bots are indexing your transferred site correctly.