This study aimed to determine the proportion of probiotic fermented soya waste in the diet on feed intake, nutrient digestibility, rumen parameters, and nitrogen retention of goats. The difference in treatments was probiotic fermented soya waste (FSW) levels replacing concentrate at 0, 25, 50, 75, and 100% (dry matter basic) corresponding to FSW0, FSW15, FSW50, FSW75, and FSW100, respectively. A result as dry matter intake tended to be low in FSW100 (p>0.05) but crude protein consumption was not different (p>0.05) among treatments. Although the digestibility of FSW100 was higher than FSW0 for DM, OM, and CP it was not different in this study. The pH, NH_3, and VFAs at 0h and 3h were similar (p>0.05) among treatments. However, nitrogen retention had an increasing tendency followed by the increasing of the ratio of FSW in the diet from 6.98 to 7.59, 7.85, 7.45, 7.28 g/goat/day corresponding to FSW0, FSW15, FSW50, FSW75, and FSW100. Therefore, probiotic soya waste fermentation could replace concentrate, and at the ration replacement of 50% was the best for utilization in goats.