This study aimed to evaluate the relationship between gut probiotic flora and nonalcoholic fatty liver disease in a diet-induced rat model, and to compare the effects of two different probiotic strains on nonalcoholic fatty liver disease. Forty male Sprague-Dawley rats were randomized into 4 groups for 12 weeks: control (standard rat chow), model (fat-rich diet), Lactobacillus (fat-rich diet plus Lactobacillus acidophilus), and Bifidobacterium (fat-rich diet plus Bifidobacterium longum) groups. Probiotics were provided to rats in drinking water (10¹⁰/ml). Gut bifidobacteria and lactobacilli were obviously lower at weeks 8 and 10, respectively, in the model group compared with the control group. Supplementation with Bifidobacterium significantly attenuated hepatic fat accumulation (0.10 ± 0.03 g/g liver tissue) compared with the model group (0.16 ± 0.03 g/g liver tissue). However, there was no improvement in intestinal permeability in either the Lactobacillus or the Bifidobacterium group compared with the model group. In all 40 rats, the hepatic total lipid content was negatively correlated with gut Lactobacillus (r = −0.623, p = 0.004) and Bifidobacterium (r = −0.591, p = 0.008). Oral supplementation with probiotics attenuates hepatic fat accumulation. Further, Bifidobacterium longum is superior in terms of attenuating liver fat accumulation than is Lactobacillus acidophilus.