In this research the effect of Bioplus B2 probiotic and galactooligosaccharide prebiotic (GOS) on performance, egg quality, and some blood parameters of commercial laying hens were investigated in a sample of 216 hy-line laying hens (w36) with the same average weight aging 50 to 62 weeks for a period of 12 weeks in a completely randomized design with 6 treatments, 6 replications and 6 hens per each replication in the cage system. Experimental treatments included 1) without additives (as control), 2) diets containing 0.1% Bioplus B2 probiotic, 3) to 6) diets; containing, 0.05, 0.1, 0.15 and 0.20 % of galactooligosaccharides prebiotic, respectively.  The results indicated that both egg weight and mass was increased significantly (P<0.05) in the Bioplus B2 probiotic treatment. Egg production percentage, feed intake and feed conversion ratio were not significantly influenced by treatments. Using galactooligosaccharide at the levels of 0.05, 0.1 and 0.2 percent improved dry eggshell weight significantly while the levels of 0.05, 0.15 and 0.2 percent increased eggshell weight per unit area compared to the control (P<0.05). Total protein and albumin of serum increased in the Bioplus B2 treatment (P<0.05). Using Bioplus B2 probiotic and 0.15% galactooligosaccharide significantly decreased blood cholesterol level (P<0.05). In general, the results showed that the using of prebiotic galactooligosaccharide at the level of 0.15 % increases the weight of eggshell per unit area, decreases the blood serum cholesterol, and improves some performance traits compared to control group, therefore it can be used instead of probiotic Bioplus B2.