From Longman Dictionary of Contemporary Englishread up on something (also read something ↔ up British English) phrasal verbREADto read a lot about something because you will need to know about it You’ll enjoy traveling more if you read up on the history of the countries you’ll be visiting. → read→ See Verb table
Examples from the Corpus
read up on • Or is it something serious you need to read up on?• Why not just read up on away reports from last season instead?• Probably it would be a good idea to read up on free drop rules before the round!• She read up on rape and rapists at the library.• But afterwards, in the Institute, I also read up on the Catherine Palace.• Shirley Coates recommends reading up on the company and preparing a list of questions that go beyond pay and holiday.• Spicer started reading up on the possible coarsening effects of media violence on young children. 