The study was supposed to discover the cognitive processing mechanism of MLD. Math learning disability (MLD) is an important area of learning disability, accounting for large percentage of students in the middle school. Now there emerges a leading paradigm for carrying out research on MLD from the viewpoint of information processing. The study was designed the find out whether the MLD students have domain-general deficit on the cognitive processing when they solve the math problem or they have specific mechanism. The criteria for defining the MLD or math learning disorder of this study is: the math score was lower than 20% of the total score, with normal IQ, and without the obvious organic deficit, emotional disorder and learning motivation disorder. Based on the three-factor model put forward by Baddeley and Hitch (1974), this study designed the experiment tasks of the stop signal task and Flanker tasks to exploring the differences of the central executive system of working memory. There are 111 students participating the study, with 55 MLD students and 56 students who are good at math (with 46 male students and 68 female students, average age is 11.97-year-old). The tasks were designed on the computer by E-prime software. Each participant spent 30 minutes finishing the experiments with the guide of psychological graduate students. The results of Stop signal task showed that MLD students have lower score than students good at math on the conditions of SOA10ms (t=-3.48, p<0.01), SOA70ms (t=-4.08, p<0.001), SOA150ms (t=-3.11, p<0.01) and SOA230ms (t=-2.28, p<0.05), but with no significant difference on the condition of SOA300ms (t=-1.586, p>0.05). The results of Flanker task showed two groups have significant difference on the accuracy of tasks (t=-4.05, p<0.001). The regression analysis indicated that the interference conditions can better predict math achievement than the conditions without interference. The developmental trend of central executive ability among the junior school students grew with age, but two groups had different shapes. The students good at math development smoothly, however, the MLD students fluctuated on the 7-grade. The conclusion of the study was the MLD students couldn’t finish the tasks with high loaded working memory demand, but they were capable to finish some simple cognitive tasks, which meant that the counter interference and attention control abilities deficit was the core deficit in the MLD.