Abstract: To investigate the light response and acclimation of Forsythia suspensa in seedling stage,improving seedling quality and production,one year old Forsythia suspensa seedlings were selected to test under four light intensities (100%,50%,25% and 12.5% relative transmittance levels) under field conditions. Survival rates,photosynthetic traits,morphology,biomass accumulation and allocation patterns of these seedlings after one growing season were measured. The results showed that at 50% relative transmittance level,the maximum net assimilation rate (Amax),light saturation point and chlorophyll b content of one year old Forsythia suspensa seedlings decreased significantly,but seedling height (H),root collar diameter (RCD),total root length (RL),root surface area (RS) and biomass accumulation of all organs significantly increased,while root mass ratio (RMR) decreased and stem mass ratio (SMR) and above/ belowground mass ratio increased. At 25% relative transmittance level,survival rates,Amax,H,RCD,RL,RS and biomass accumulation of all organs of the seedlings significantly increased and were highest among all light intensities, while only SMR increased in all biomass allocation variables.Moreover,at 12.5% relative transmittance level,only Amax,RCD,RL,RS significantly increased with smaller increments than that at 50% and 25% relative transmittance levels,while only leaf mass ratio (LMR) decreased in all biomass allocation variables. Therefore, one year old Forsythia suspensa seedlings showed inconsistent photosynthetic responses to all shade treatments and consistent morphological and biomass accumulation responses to medium shades,and were capable of acclimating medium shade by increasing biomass allocation of aboveground structure. Thus,the light requirements and habit of Forsythia suspensa in seedling stage should be emphasized in future management works of nurseries.