The disclosure discloses a method for preparing battery-grade nickel-cobalt-manganese sulfate crystals from low nickel matte, which includes the following steps: S1, sequentially performing high-pressure leaching, iron-aluminum removal and nickel-cobalt-manganese precipitation treatment on laterite nickel ore to obtain an underflow containing nickel-cobalt-manganese hydroxide, wherein the pH value of the underflow is 7-8; S2, performing oxygen-pressure leaching on the low nickel matte using sulfuric acid and oxygen to obtain a leached slurry containing residual acid, adding the underflow into the leached slurry to obtain a mixed slurry, and adjusting the pH value of the mixed slurry to be 3-5 using the underflow; and S3, performing filter pressing on the mixed slurry to obtain filtrate and tailings, and performing nickel-cobalt-manganese co-extraction, concentration and crystallization on the filtrate to obtain the nickel-cobalt-manganese sulfate crystals. The method has the advantages of high utilization rate of nickel, cobalt and manganese, few impurities, reduced reagent consumption and technological processes, and high transportation efficiency.