Photostimulation affects a range of physiological and behavioral characters in birds. However, whether such changes would be affected by photoperiod largely remain unknown. In order to reveal the role of photoperiods in mediating the responses of male Java Sparrow (Lonchura oryzivora) to photostimulation, a total of 18 Java Sparrows were randomly separated into three groups with each containing six individuals. These three groups were housed in separate chambers and exposed to mid photoperiod (12L︰12D, supplemented with artificial lights between 6:00 to 18:00), artificial long (16L︰8D, lights on 6:00 to 22:00) and short (8L︰16D, lights on 6:00 to 14:00) photoperiods respectively. In either case, artificial lights were provided with white fluorescent lamps (light intensity at cage level 550 lx) which were operated by automatic programmed devices. After 30 days, the birds belonging to each photoperiodic group were subsequently separated into two subgroups each with three individuals. Each photoperiodic experiment group was provided uninterrupted light for 72 h and the control group remain unchanged with the behavior in both groups being completely monitored by digital cameras. The quantity of corticosterone in serum was estimated by ELISA Kit and serum proteins were separated and identified by SDS-PAGE electrophoresis after 72 h photostimulation. Videos were then analyzed, with the length of all kinds of behavior (activity, nest, petch, feeding and preening) being recorded. Behavioral data and the changes of corticosterone were analyzed by two-way analysis of variance (ANOVA). The migration rate of SDS-PAGE gel (Rf value) was calculated, and the serum protein zoning was divided according to the range of Rf. The results showed that: 1. Photoperiod affected the behavior of Java Sparrow (Fig. 1). 2. Photoperiod affected corticosterone hormones in male Java Sparrow, with the response of corticosterone in mid photoperiod differed from the other two photoperiods (Fig. 2). 3. Serum protein components were affected by photoperiod (Table 1). All these results suggested that photoperiod mediated physiological responses of male Java Sparrow to photostimulation.