How do you express "no matter" in Chinese?

Firstly, there are two expressions that you can use to express "no matter", these are:

1.不管 (bùguǎn) ……，都(dōu) /也 (yě)……       OR      2. 无论(wúlùn)/不论(bùlùn)……，都(dōu)/也(yě)……

The first one is more informal than the second one, but both can use in the same way, 都/也 are used in the second part of the sentences to emphasize the action or decision (consequence). Let's see some examples of structure:

不管你承不承认，你都是最棒的。 (Whether/no matter you agree or not, you are still the best.) Here the construction of the sentence is :  不管+ {Clause ： Subject （你）+Verb expression/ question word （承不承认）, Subject （你）+都 + inevitable result （是最棒的）

不管多贵，他都要买。 (No matter how expensive is, he's still buying it)

The structure of this sentence is:  不管+多+Adjective （贵）， Subject （他）+都 + Inevitable result （要买）

Turning to 无论/不论……，都/也……：

无论 means "no matter", 都/也 are used same as with the previous one, to emphasize the action or decision which leads to the inevitable result. As said before, 无论 means ”no matter" so the clause that follows will normally include interrogative pronouns.

Here is an example:

无论你吃什么，你都会胖。 (No matter what you eat, you will still gaining weight) 

无论+ {Clause：Subject （你）+Verb（吃）+Interrogative pronoun （什么）}, Subject （你）+都+ Inevitable result （会胖）