I have an Australian travel document for refugees. Do I need a visa to travel to USA ? If I need, can I apply for a visa ?
Visa-free entry to the USA is only available if you are a national of a VWP country, and present a passport issued by that country.
A refugee travel document is, by definition, issued by a different country than the traveler's nationality -- so travelers on refugee documents are never eligible for visa-free entry.
Thus: You need a visa.