One experiment was carried out to evaluate effects of dietary neutral detergent fiber (NDF) concentrations on feed intake, nutrient digestibility and rumen parameters of Bach Thao goats based on NDF source from Brachiria multica grass. A Latin square design with 5 treatments and 5 male goats from 19.8-26.5 kg was used for this experiment. Five treatments were dietary NDF concentrations of 55, 59, 63, 67 and 71%. The results showed that feed intake, dry matter digestibility (DMD) and organic matter digestibility (OMD) were significantly linear decreased (R2 >0,80 and P<0,05) following by increasing dietary NDF concentrations from 55 to 71% . There was no significant differences (P>0.05) of ruminal NH3-N, while there was a significant increase (P<0.05) of rumen pH value among the treatments. The VFAs concentration, although, was not significant different (P>0.05) among the treatments, there was a tendency of linear reduction following by the increase of dietary NDF concentrations by the function Y= - 0.325 X + 119 (R2 = 0.883, P=0.011 and SE=0.737). The daily weight gain was significantly reduced for the treatment of NDF71. It is concluded that dietary NDF concentration of Bach Thao should be from 63 to 67% for better growth requirement and efficient utilization of the Para grass. Key words small ruminants, roughages, feed utilization, fiber digestion, rumen parameters