To get your Thai girlfriend a visa, first you must choose what visa is most suitable for her to travel. If you are intending on marrying your Thai girlfriend in Australia, then you could apply for a fiancée visa, though if your Thai girlfriend has not visited you in Australia before it is advised to apply for a Tourist visa first.

Your Thai girlfiend can travel to Australia with a tourist visa and will be able to stay for 2 years, but again if your Thai girlfriend has not been to Australia before it would be advised to apply for a 3 month tourist visa.

How Do I Get Thai Girlfriend Visa

Your Thai girlfriend will have to make the visa application in Bangkok to get a thai girlfriend visa.

The visa application will have to be translated and certified.
The Australian boyfriend – sponsor will have to write both a sponsorship letter and an intention of stay letter to the immigration

There will have to be substantial proof of a relationship, which will include photos, phone calls, emails, text messages and receipts for money sent to your Thai girlfriend.
Your Thai girlfriend will have to provide evidence to suggest she has good reasons and intentions to return to Thailand.

Your Thai girlfriend will have to demonstrate that she is not involved with human trafficking.
Remember any evidence you provide the Australian embassy at the time of the visa application cannot be withdrawn, any statement that cannot be backed up with evidence will be held on file at the embassy and held against your Thai girlfriend

If you are found to provide false evidence or lie while making the visa application, your Thai girlfriend could be banned from travelling to Australia for 5 years.