Examples of probiotic that can promote host health by improving its intestinal microbial balance and intestinal immunity belong to the genus Lactobacillus.Bursin (BS) is a peptide isolated from bursa of Fabricius (BF) as an adjuvant for a variety of immunogens.To investigate the synergistic effects of Lactobacillus plantarum (LP) dietary supplementation and BS immunization on production performance, immune characteristics, antioxidant status, and intestinal microflora in broilers, 200 one-day-old broilers of mixed sex were randomly allocated into 4 treatments in a 2×2 factorial arrangement (LP-/BS-, LP-/BS+, LP+/BS-, LP+/BS+) for 42 days.BS immunization enhanced immune response by increasing serum total IgG concentration and IL-6 concentration, promoted antioxidant capacity by increasing CAT activities in serum and liver and decreased serum MDA content at 42 day of age (DOA), enriched intestinal microflora diversity.LP supplementation enhanced immune response by increased IL-2 concentration at 42 DOA, promoted antioxidant capacity by increasing liver CAT activities, increasing GSH-Px activities in serum and liver at 21 DOA, and decreasing serum MDA content at 42 DOA, promoted intestinal mieroflora composition by decreasing total aerobes and E.coli counts at 21 DOA, increasing total anaerobes count at 21 DOA, increasing Lactobacillus spp.and Bifidobacterium spp.counts at both 21 and 42 DOA.There were significant interactions between BS and LP on daily body weight gain (BWG) and feed conversion ratio (FCR) in the starter period (1 to 21 DOA), IL-2 concentration and liver MDA content at 21 DOA, thymus index (TI), peripheral lymphocyte proliferation and E.coli counts at 42 DOA.Overall, these data suggested that the combination of LP dietary supplementation and BS immunization promoted the production performance, immune characteristics, antioxidant status, and intestinal microflora of broilers.