Midday gerbil (Meriones meridianus) and Northern three toed Jerboa (Dipus sagitta) are two dominant sympatric species in Alashan desert. Studying their activity rhythms is important for understanding the coexistence mechanism of desert rodents. This study was conducted in the Alashan desert of Inner Mongolian, on April (spring), July (summer), September (autumn) and October(pre-winter), 2017. We monitored M. meridianus and D. sagitta using camera-traps in order to understand the active rhythms in different seasons and explore coexistence strategies of two species. The results showed that: (1) The population of M. meridianus was restrained by the D. sagitta population density. An obviously staggered phenomenon was found between the two species peak activity. Affected by the light intensity, the activity time of two species was positively correlated with night length. The activities start time of the two species was positively correlated with the sunset and ambient temperature. (2) There was no significant season difference in activity intensity of M. meridianus. However, the D. sagitta showed the opposite strategy (F =3.202；P =0.032); (3) These result indicated that coexisting desert rodents adjusted their night time utilization patterns to reduce competition and achieve coexistence.

子午沙鼠（Meriones meridianus）和三趾跳鼠（Dipus sagitta）是阿拉善荒漠区同域共存的两种优势鼠种，研究其活动节律对于了解荒漠啮齿动物的共存机制具有重要意义。本研究于2017年4月（春季）、7月（夏季）、9月（秋季）和10月（初冬）在阿拉善荒漠区，利用红外相机陷阱技术对子午沙鼠和三趾跳鼠的活动节律进行监测，以期深入了解极端干旱环境中子午沙鼠和三趾跳鼠不同季节活动节律动态，探索优势鼠种共存策略。结果表明：（1）子午沙鼠的种群数量受三趾跳鼠种群密度的抑制，其活动高峰期随三趾跳鼠活动高峰期的推迟而推迟，存在明显错峰现象，受光照强度的影响，二者的活动时长与夜长均呈正相关关系，其活动开始时间随日落时间的推迟、环境温度的升高而推迟；（2）子午沙鼠的活动强度在不同季节间无显著差异，三趾跳鼠的活动强度在不同季节有显著差异

（F=3.202；P=0.032)，表现为4月>7月>9月>10月；（3）子午沙鼠和三趾跳鼠通过调整其夜间时间利用模式以减少竞争，实现同域共存。