An angle-adjustable aroma-diffusing night lamp system includes an electrical plug unit, a lamp socket unit, a collar coupled to a front coupling neck of the housing of the electrical plug unit and affixed to the housing of the lamp socket unit for allowing rotation of the lamp socket unit relative to the electrical lug unit within a predetermined angle, a spring-supported latch installed in the housing of the electrical plug unit to lock the electrical plug unit to the collar in one of a series of angular position, and a lampshade coupled to the lamp socket unit around the lamp bulb in the lamp socket unit and holding a fluid aroma substance for heating by the radiation heat from the lamp bulb into vapor.