stickler
noun [ C ] informal uk/ˈstɪk.lər/ us/ˈstɪk.lɚ/
非常注重（某种行为）的人；固守…的人
a person who thinks that a particular type of behaviour is very important, and always follows it or tries to make other people follow it
He's a stickler for detail/accuracy/efficiency. 他非常注重细节／精确性／效率。