What is this flower?

[andy2019]

I heard this flower is pretty popular in Vietnam. I don't know what the name of it in English

 

[Twigs]

Looks like Dragon Fruit.

 

[Palmlin]

Hi, Andy2019,

It looks a lot like Night Blooming Cereus (also called Queen of the Night). It's a cactus that blooms around 9 or 10 p.m. and is fully open by midnight and usually closes at sun up. What's baffling is that it appears to be daylight in your picture and the bloom is still open...