I have mysql dump file. How I can import this file into mysql using php?
You dump is probably a file that just contains a lot of SQL queries.
The simplest way to import such a dump is to use the mysql command-line client (especially if the file is big !) :
mysql --user=USERNAME --password=PASSWORD --host=HOST DB_NAME < /path/to/your/file.sql
If you can connect to your server with some command-line access (typically, using ssh), that's the way to go.
Else, I suppose you could execute such a command with system()