Deception is common in dementia care, although its moral legitimacy is questionable. This paper conceptually clarifies when does dementia care involve deception and argues that care ethics is an appropriate ethical framework to guide dementia care compared with the mainstream ethical theories that emphasize abilities. From a perspective of care ethics, this paper claims that morally defensible deception is context-specific, embodied as a caring process that needs to be identified through instant, creative and interactive care procedures. According to this argument, it further analyses and concludes the moral rationality of deception in five common cases. While deception is morally justified in many situations, another concern is that it is usually not the last resort but a means of convenience. As the ability to interact, autonomy and dignity of persons with dementia (PWDs) are generally ignored; nurses need more training and education to master the essential procedures to ensure that the value of authenticity and autonomy is maintained and considered throughout dementia care.