I would like to petition my sister on my father's side but her birth certificate don't show a father nor my father's name.. My father is long gone how would I prove she is my sister. Would immigration department accept siblings DNA?

You need to know the policy of the country you want to go to regarding the policy you are coming from (and it isn't clear which one of you wants to immigrate).
To do a DNA test requires DNA of a male family member common to both women. Female DNA doesn't give direct lineage. Once you determine who that closest male is (it can even be a male child of yours or hers), then ask immigration on their website. If you can't, you will probably need to pay a lawyer because of the complication of the DNA issue.

Ok, in that case sorry for not specifying or not being more clear.. This would be an edit of the question above...

I am a US citizen and I would like to petition my sister on my father's side to come to the US from the Dominican Republic. But her birth certificate don't show a father nor my father's name.. My father is long gone... How would I prove she is my sister? Would immigration department accept siblings DNA?

Find all KNOWN (on official documents) close relatives of you, your sister, and your father. Then pay a DNA testing lab to test as many of you as immigration wants.
You have to contact US Immigration because it will be an unusual situation. We can't do it for you.

If your father has no documented living parents, siblings, or other children, then it's hopeless, sorry.

Don't jump to a conclusion and pay for DNA test as yet. DNA test can be done only by order of the consul, and must be done at certain place, by certain specialist, not by anyone.

This is a complicate situation, and will need more details...