Capillary array electrophoresis (CAE) is founded with the laser induced fluorescence detection (LIFD) system. The same model as the detection system is simulated in Tracepro and the stray light caused by capillaries is analyzed. The stray light distribution of the observation surface is plotted when the laser scans the different sections of a capillary in the array. The results of simulation indicate that the stray light is strongest when scanning the inner center of a capillary and decreases at edges; in two cases (50μm and 75μm inner diameter, ID) when the ID is larger, the stray light is stronger as a whole. Different ID of capillaries which affects the stray light is analyzed; considering many factors, 50μm ID of capillary is appropriate. Based on the analysis of stray light cross-talk by other capillaries in an array, the spacing between capillaries in an array is suggested more than 50μm which the stray light is steady-going and simple to operate. The results can be helpful for the mode of the laser scanning different capillaries in an array sequentially.