There is no Australian Embassy in Mongolia as you might know. The Australian representation is located at the Australian Embassy in Beijing. If you are in Mongolia then you will need to contact the Australian Embassy in China for assistance. They will be able to assist you with consular assistance when needed.
If you want to apply for an Australian Visa in Mongolia be this a visitors visa or a marriage visa then you will need to file all your paperwork at the Australian Visa Application Centre in Ulaanbaatar which has been listed below with a map the its location. Note also the contact details and their office hours.
If you have any questions about a passport then see the listing for the Australian Embassy in Beijing. If it is about a visa and not consular assistance then see the email below for the visa application centre for more details.
Australian Visa Application Centre Mongolia
DHL House 1st Floor, 1st Khoroo,
Peace Avenue 10/5, Ulaanbaatar Mongolia
Telephone: +976-7000 4453, +976-8688 4453
Fax: +976-7010 4410
The AVAC is open from 8.00am until 3.00pm, Monday to Friday (excluding public holidays). A telephone enquiry services is available from 9.00am until 3:00pm, Monday to Friday.