Two ways to view PDF on PSP

First, Convert every PDF page to image(for example jpeg), and view Jpeg on PSP,
PDF2PSP is a tool for converting PDF documents and print outs into JPEG images suitable for displaying on the Sony PSP handheld game console.
Second, directly View the really PDF on PSP, and you need Bookr,A document reader for the Sony PSP with native PDF rendering.
To use Bookr, you need a Sony PSP with firmware version 1.5, other firmware versions are not supported.
To install Bookr, simply copy the __SCE__bookr and %__SCE__bookr folders to your Memory Stick \PSP\GAME folder.