Objective To understand various behaviors of Microtus fortis under different environment lighting stimulation and collect the basic data for formulating the environmental control standard in breeding Methods Three groups of Microtus fortis were observed using the special apparatus for animal behavior observation under different environment light stimulation. Results The 24D group was at most in locomotor activity and the 24L group was at least. The 12L/12D group was at near the 24D group. No obvious and clear rhythmicity of locomotor, whether in group 24L or in group 24D,was found during lighting treatment; but under 12lL/12D condition, the locomoter appeared quite regular and increased with the time of lighting, The 12L/12D group was several times as much as in the other two groups in play behavior and the 24D group was more than the 24L group . The vole was very few in the center under condition of 24L. but animals were shuttled to the central in 24D and 12L/12D lingting. The 12L/12D group was much more at feeding and drinking while the 24L group was very little. Conclusion Indoor regular environmental light treatment, the behavior of Microtus fortis has inherence in photoperiod response. The 12L/12D group is the most suitable light environment for Microtus fortis. 〔Key words 〕Microtus fortis；environment lighting；locomotor；rhythmicity；suitable environment