The magnetic properties and magnetocaloric effects(MCE) of Ho Ni Ga compound are investigated systematically.The Ho Ni Ga exhibits a weak antiferromagnetic(AFM) ground state below the Neel temperature TNof 10 K, and the AFM ordering could be converted into ferromagnetic(FM) ordering by external magnetic field. Moreover, the field-induced FM phase exhibits a high saturation magnetic moment and a large change of magnetization around the transition temperature,which then result in a large MCE. A large-?S_M of 22.0 J/kg K and a high RC value of 279 J/kg without magnetic hysteresis are obtained for a magnetic field change of 5 T, which are comparable to or even larger than those of some other magnetic refrigerant materials in the same temperature range. Besides, the μ_0H~(2/3)dependence of |?S_M~(pk)| well follows the linear fitting according to the mean-field approximation, suggesting the nature of second-order FM–PM magnetic transition under high magnetic fields. The large reversible MCE induced by metamagnetic transition suggests that Ho Ni Ga compound could be a promising material for magnetic refrigeration in low temperature range. The magnetic properties and magnetocaloric effects (MCE) of Ho Ni Ga compound are investigated systematically. Ho Ni Ga exhibits a weak antiferromagnetic (AFM) ground state below the Neel temperature TN of 10 K, and the AFM ordering could be converted into ferromagnetic (FM ) ordering by external magnetic field. Moreover, the field-induced FM phase exhibits a high saturation magnetic moment and a large change of magnetization around the transition temperature, which then results in a large MCE. A large-? S_M of 22.0 J / kg K and a high RC value of 279 J / kg without magnetic hysteresis are obtained for a magnetic field change of 5 T, which are comparable to or even larger than those of some other magnetic refrigerant materials in the same temperature range. Besides, the μ_0H ~ (2/3) dependence of |? S_M ~ (pk) | well follows the linear fitting according to the mean-field approximation, suggesting the nature of second-order FM-PM magnetic transition under high magnetic fields. The large reversible M CE induced by metamagnetic transition suggests that Ho Ni Ga could could be a promising material for magnetic refrigeration in low temperature range.