An 8-week feeding experiment was designed to examine the influences of single or/and double strains of probiotic compared to antibiotic colistin on growth, hematological variables, blood serum metabolites and caecal fermentation in post-weaning rabbits exposed to heat stress conditions. A total of one hundred (35-day-old; average initial body weights 694±7.33) New Zealand White rabbits were distributed into five groups. The experimental groups were: the basal diet (control), or basal diet fortified with 120mg colistin (COL); 5 * 106 cfu Clostridium butyricum (CB); 2 * 108 cfu Enterococcus faecium NCIMB 11181 (EF); or 2.5 * 10 6 cfu C. butyricum +1 * 108 cfu E. faecium/kg diet (CB+EF). The results demonstrated that both the EF and CB+EF treatments enhanced (p < 0.05) final body weight and overall feed conversion ratio compared to control and COL treatment. The carcass yield percentage and relative organs weight were insignificantly affected in all treated groups. The COL treatment increased (p < 0.05) mean corpuscular volume and albumin/globulin ratio compared to the control. Compared to the control, all probiotic and COL groups decreased (p < 0.05) serum total triglycerides and very low-density lipoprotein. The concentrations of Serum total protein, globulin, high-density lipoprotein, complement component 3, and lysozyme activity were higher (p < 0.05) in probiotic groups than those in the control group. Probiotic application improved the caecal total volatile fatty acids, propionate concentrations, and intestinal histomorphometry parameters. In conclusion, EF and CB+EF probiotic supplements could be used as alternatives to antibiotic colistin to enhance the growth and health of weaned rabbits under heat stress conditions.