Purposes: The animacy effect refers to the positive influence of animate stimuli on memory. This effect is found in free recall, recognition and cued recall tasks. Some researchers put forward the animate monitoring hypothesis, assuming that animate stimuli probably attract more attention and get better remembered. However, other researchers argued that the organizational structures of animate stimuli lead to the animacy effect, which is known as the categorical hypothesis. It is not clear about the difference between the effects of animacy and category on true and false memory. Thus, the present research discussed the mechanism underlying anmiacy effect and tried to distinguish the difference between the effects of animacy and category on true and false recognition memory. Moreover, this research examined how long the two effects could last. Procedures: The research included two experiments. The materials were the same in the two experiments, including 30 words for animate things, fruits and inanimate things in multiple categories, respectively. There were 24 subjects in the experiment1 and 56 subjects in the experiment 2. Experiment 1 examined the memory advantage of animacy under the situation where the stimuli were presented by blocks according to their category attribute (e.g., presenting all animate things and then all fruits) and the orders were counterbalanced. Experiment 2 examined the memory advantage of animacy under the situation where the stimuli were presented pseudo-randomly to prevent the same category attribute to appear in succession. This manipulation could avoid subjects to use the categorical encoding strategy. In order to examine how long the effects last, the final recognition test was taken immediately after the distractor phase or one day after learning in experiment 2. Both experiments consisted of three phases: study phase, distractor task phase and test phase but the distractor task phase was replaced by a 24-hour interval in the delayed-test group in experiment 2. During the study phase, participants were asked to remember the words presented in the center of the screen, each for 3s after a fixation for 800ms. Then participants finished a 5-min distractor task in which they made mathematical calculations, followed by a recognition task. For the recognition task, participants were instructed to recognize the just-studied and new lists of words and the words would not disappear until participants responded. Results: (1) When the categorical attribute was apparent, the effects of animacy and category on true recognition memory were equivalent; (2) When the categorical attribute was not apparent and the recognition test was taken immediately, the effect of animacy on true recognition memory was strongest. However, when the final recognition test was taken one day after learning, the effects of animacy and category on true recognition memory were equivalent again. (3) The category effect facilitated true recognition memory and created more false recognition memory while the animacy effect only facilitated true recognition memory; (4) The category effect and animacy effect were both found in the immediately-test group and delayed-test group. Conclusions: (1) The mechanisms underlying the category effect and animacy effect are different; (2) The mechanism of animacy effects on true and false memory are different; (3) Both category effect and animacy effect can last for more than 24 hours but animacy effect declines faster.