This experiment was conducted to investigate the effects of Lycium barbarum polysaccharides (LBP) on slaughter performance, immune organ development and meat quality traits of growing Rex rabbits. Eighty 40-day-old Rex rabbits (half male and half female) were randomly allocated into 4 groups (each group had 20 replicates and each replicate had 1 rabbit). The rabbits in control group were fed a basal diet, while the rabbits in experimental groups were fed the basal diet supplemented with 0.1%, 0.2% and 0.3% LBP, respectively. The pre-feeding period lasted for 5 d followed by an experimental period of 30 d. The results showed as follows:1) compared with the control group, the half eviscerated rate and all eviscerated rate of experimental groups had improved, but the differences were not significant (P>0.05). 2) The spleen index was increased with the increase of LBP supplemental level, and the highest value of spleen index was found in the 0.3% group and the highest value of thymus index was found in the 0.2% group, but no significant differences in them were found among all groups (P>0.05). 3) Compared with the control group, the drip loss rate, cooking loss rate, shear force and brightness (L^*) value of muscle of experimental groups were decreased slightly, and the pH of 45 min and pH of 24 h after slaughter were increased slightly, but the differences were not significant (P>0.05). Compared with the control group, the redness (a^*) value of muscle of 0.1%, 0.2% and 0.3% groups were increased by 1.85%, 5.86% and 10.80% (P>0.05), respectively, and the yellowness (b^*) value of muscle of 0.1%, 0.2% and 0.3% groups were decreased by 10.79%, 7.39% and 11.93% (P>0.05), respectively. The results indicate that diet supplemented with LBP has no significant effect on the slaughter performance of growing Rex rabbits, which can improve the immune organ indexes and improve the meat quality traits at a certain extent, and the recommend supplemental level is 0.3%.