Chemical signals provide important cues in social behavior of many mammalian speciesly, mediating sexual, aggressive, parental and spacing behavior, as well as influencing an animal's internal hormonal milieu. Conspecific novel male's substrate was given as individual odor stimulus to adult male Brandt's voles(Microtus brandti) that left in individual cases in long-|photoperiod (LD) and short-|photoperiod (SD) resfectioely. The plasma testosterone of these male actors was mensurated by radioimmunoassay. The results indicated that plasma testosterone increased with the duration that the male vole was exposed to the odor of  a novel male. Plasma testosterone concentration in LD males increased sigrificanily than those in SD males in 30  minutes.After 1 hour or 2 hours, exposed to the novel scents, the testosterone levels of LD males were higher than SD males, but didn't show significant difference. The results demonstrated that the chemical signals induced releasing of androgen and the increase of plasma testosterone of males voles exposed to novel conspecific odors was also influenced by the photoperiod. It suggest that the change of testosterone concentration would underlie the odor producing and odor preferences of Brandt's vole.