Working memory refers to the cognitive capacity to temporally store and manipulate sensory information from multiple sensory domains. Recent research shown that aging effect had extensive influence on working memory; however, which aspect of cognitive function leads to the aging effect is still unclear. To investigate the influences of process speed on aging effect, the present study used a modified visual spatial task to evaluate the capacity of working memory with older and younger subjects, and we compare the performance of two different age group with same experimental parameters. Our results showed that the performance of older subjects in visual spatial task were increased with the present time of stimulus. Remarkably, the older subjects' item capacity of working memory could approaching with younger subjects in 500ms presentation condition. These results suggested that aging effect in visual spatial task was probably caused by processing speed and the tempo of trails, thus opening a wide range of applications for the training method about working memory for older subjects to anti-aging effect on cognitive domain.