In the situation of the same throwing quantity in the concentrated feed, 3 months old Hainan black goats were fed with 4 kinds of forage grasses. The result indicated that the allocated proportion structure like Pennisetum×P.americanum cv. Reyan No 4:Paspalum atratum cv. Reyan No 11:Stylosanthes guianensis cv. Reyan No 5: Panicum maximum jacq cv. Reyan No 8=2.35: 1.1: 0.95: 0.6 had good fattening effect and had a remarkable difference with feeding with conventional forage grass of fattening in the goat field. In the situation of feeding with the same forage grass, different throwing quantity of concentrated feed was provided to the lamb of Hainan black goat. The result indicated that, with increase of the concentrated feed’s recruitment, live weight gain per day also increased. But in the aspect of the economic efficiency, feeding the 300g concentrated feed per day had the highest fattening profit. This test result will provide a basis for reasonable, high effective, economical fattening for lamb of Hainan black goat.