Conventional wisdom indicated that implicit memory is a kind of automatic processing. However, recent studies found that implicit memory was more vulnerable to be distracted than explicit memory in some conditions. Therefore, it’s not clear on the processing mechanism of implicit memory. In order to find out this confusion, we can use variables that have different effects on the automated processing and controlled processing. Previous studies have found that cognitive fatigue would have a strong impact on the controlled processing, but less on automated processing. However, few studies have researched the effect of cognitive fatigue on implicit memory. So, does different effects of cognitive fatigue on the implicit memory and the explicit memory? Effects of cognitive fatigue on memory were assessed by drawing a comparison between the participants with cognitive fatigue condition and that without. We used lexical decision task and lexical recognition task to tested implicit memory and explicit memory, respectively. Thirty participants were recruited in the experiment. All of them participated in experiments on two occasions, 2 days apart at least, once in fatigue condition and once in rest condition. They carried out pre-test before formal test for ensuring the validity of the experimental results. The pre-test setting was same as the formal test. In fatigue condition, participants carried out pre-test first. After that, they carried out the fatigue task that contains 320 calculation questions. Then they carried out formal test. In the rest condition, participants rested between the pre-test and the formal test. Participants were instructed to make response to appropriate items by pressing keyboard. The Reaction Time and Accuracy data in retrieval phase were recorded, in order to assess implicit memory and explicit memory. Results showed that implicit memory performance declined under fatigue condition, but the explicit memory performance was not. In the explicit memory performance, the results of present study are consistent with previous results. Cognitive fatigue didn’t affect explicit memory [F(1,29)=0.119, p=0.732]. But implicit memory was affected by cognitive fatigue [F(1,23)=9.816, p＜0.01, ηp2=0.253]. The performance of implicit memory significantly decreased after the fatigue task. It reflected that implicit memory is more vulnerable to cognitive fatigue than explicit memory. In conclusion, results from the present study revealed that effects of cognitive fatigue on implicit memory and explicit memory were different. Implicit memory is more sensitive to cognitive fatigue than explicit memory. The results of present study are clearly inconsistent with the traditional views. Conventional wisdom thought that implicit memory was a kind of automatic processing, which could immune to effects of cognitive fatigue. But in present study, we found inverse results in which implicit memory retrieval was easier to be impacted than explicit memory by cognitive fatigue. These results revealed that although implicit memory is an automated processing. But it might own different features from other automated processing. This study firstly use cognitive fatigue to research the difference between implicit memory and explicit memory. And we found implicit memory is more vulnerable to cognitive fatigue than explicit memory. The present study provides support for further research on the processing mechanism of implicit memory.