I have a PST file, but I didn't access it in Apple Mail. So I need an EMLfile for using Apple mail. There are any method or any tool that convert my all emails into an EML file.

First of all, there is no such official or freeware solution available to convert mbox file to olm format. So I would like to suggest you to try Advik MBOX to OLM Converter. Using this application you can easily convert mbox to olm format without any assistance. The tool support mbox file created by Thunderbird, Spicebird, The Bat, Opera Mail, Gmail, Apple Mail etc. 

1. Download and install Advik MBOX to OLM Converter
2. Launch tool and add .mbox file
3. Choose output target location 
4. Click convert

Done! Now you can import .olm file to Outlook for Mac without any error.
Download : http://www.adviksoft.com/dl/advik-mbox-to-olm.exe