The only rule regarding this that I've managed to find is (PHB p190):
You can also interact with one object or feature of the environment for free, during either your move or your action. For example, you could open a door during your move as you stride toward a foe, or you could draw your weapon as part of the same action you use to attack.
If a PC has two weapons (dual wield), does he draw one or both?
Best Answer
You can only draw one weapon
The rules state:
When you choose to attack, you can draw a single weapon as part of that same action. Note how the rules specifically says "one object" and "your weapon". Also the sentence directly following this passage makes this more explicit:
Drawing one weapon is one interaction with one object. Trying to draw the second weapon would be a second interaction with a second object and thus it would require an action to perform.
There is a feat that will let you do this though
The Dual Wielder feat (PHB, p. 165) has a few benefits, one of which is:
If you had this feat, you would then be able to draw both of your weapons as part of a single Attack action.