A study was conducted at the experimental farm in Long Hoa commune, Binh Thuy district of Can Tho City to investigate effects of levels of cabbage waste (Brassica oleracea) replacement to Para grass (Brachiaria mutica) in the diets on feed ulitization, nutrient digestibility and rumen environment of growing lambs. The experimental design was a Latin square with 4 treatments, 4 periods and 4 male lambs. The treatments included 4 levels of cabbage waste replacement to Para grass (dry matter (DM)) from 0, 25, 50 and 75% (BC0, BC25, BC50 and BC75 treatments). Concentrate feed and urea were supplied to balance the level of protein in all treatments at 6.0g crude protein/kg live weight.  The results showed that DM intake of lambs was not significantly different (P>0,05) among the treatments and they were 641, 682, 717 and 677g/day for the BC0, BC25, BC50 and BC75 treatments. NDF and ADF intakes were significantly different (P>0.05) among the treatments and gradually reduced with increasing cabbage waste replacement to Para grass in diets. The metabolizable energy (ME) intake was numerically improved in the cabbage waste treatments but not significantly different (P>0.05) among the treatments. The conclusion was that replacing Para grass by cabbage waste from 25 to 75% in lamb diets did not have any adverse effects on feed digestibility and growth and rumen parameters, and the BC50 treatment was better in feed and nutrient utilization of growing lambs.