vietnamese passport

If he has a full Vietnamese passport as a Vietnamese citizen he will not need a visa or work permit.

thank you for your answer. Nice to have help.....

So he has double citizen Vietnamese and french?

And for me his wife, can i work in Vietnam? Does i need a visa and which visa?

You can come on a tourist visa but to stay for a while you need more than that.  You should read the threads on VEC and TRC.  To work you will need a Work Permit.

Also if you are staying a while, as a Vietnamese citizen, your husband must be registered in a Hộ khẩu or family registry.  I guess he could establish his own book if you intend to stay indefinitely but it would probably be easier to piggy back on their book if he has any living relatives.  He also will need a Vietnamese National ID card.  After that he can sponsor you for the VEC or TRC.  The Hộ khẩu system is an idea imported years ago from Imperial China and is a somewhat effective means of governmental population and political control.  It should be simple but it's not.  Unless he has a lot of knowledgeable relatives to guide you it might be best to see a lawyer.

Coincidentally, I once posed this question to my wife, of how a Vietnamese citizen who returns to the country with no residence and no living relatives obtains a Hộ khẩu and she couldn't even get her head around the concept.  For Vietnamese, to have no family and no hometown is incomprehensible.