Abstract: Mono-static and bi-static radar cross sections (RCS) of target reflect that whether the target could be separately detected by mono-static and bi-static radars easily. Currently, there is no quantitative index for comparison between mono-static and bi-static RCS. In this paper, definitions of RCS enhancement factor and RCS enhancement ratio of bi-static RCS relative to mono-static are given at first. Then, the two definitions are applied to analyze bi-static RCS of some stealth target and non-stealth target. The result shows that, the RCS enhancement factor is big and RCS enhancement ratio is high for stealth target, but the factor is small and the ratio is low for non-stealth target. Combined with meaning of the two indexes, it can be found that, utilization of bi-static RCS is helpful for detection of stealth target, but this effect is not obvious for non-stealth target, which is consistent with the understanding of the radar community. This also shows that the application of the above two indexes in comparison analysis between mono-static RCS and bi-static RCS is effective. In addition, according to the analysis result of bi-static RCS in narrow bi-static angle for stealth target, the detection effect can be improved when bi-static RCS in bi-static angle range from 20° to 40° is used.