Abstract: The illumination of the enclosed chicken coop needs to be controlled by artificial light, and the reduction of the illumination time during the brooding and incubation period can well control the growth of the flock. The appropriate and stable light time reduction rule can reduce the stress response of the flock so that the flock can exert greater production performance. In the brooding and incubation period, better weight standard rate and evenness can be obtained, so that the flock can play more excellent production performance.In this study, different step-by-step reduction rule tests were conducted on the illumination time of the enclosed chicken house in their brooding period. The results showed that： in the early brooding period, the illumination reduction rule that turn off the light in a fixed time and decrease the turn-on time day by day has a better effect.

Key words: brood period, illumination reduction rule, weight standard rate, evenness