In this study, tartaric acid was used to extract the valuable metals lithium, cobalt, nickel, and manganese from the anodes of waste lithium batteries. The effects of various factors, namely, acid concentration, reducing agent addition, temperature, solid-to-liquid ratio, and time, on the leaching efficiency were explored in order to determine the best conditions for metal recovery. First, the Taguchi methods were used to obtain the initial parameters and the factor weights affecting leaching efficiency. Finally, the optimal leaching parameters were obtained through confirmation experiments. For optimal leaching rates, the acid concentration is 2 mol L−1, time is 30 min, solid-to-liquid ratio is 10 g L−1, temperature is 90 ℃, and hydrogen peroxide addition amount is 1.0 vol%, resulting in leaching efficiencies of Li, Co, Ni, and Mn of 87.29, 80.51, 95.78, and 99.99%, respectively. The valuable metal cobalt can be used as a sensor material.