With the increasing demand for lead acid batteries, there were a great number of spent lead acid batteries generated. They have the dual characteristics of resource and harm, making the recovery an important. The consumption of lead reached 0.35 million tons all over the world in 2019, of which about 80%. 2.1. Experimental materialThe spent lead acid battery used in this experiment was provided by Zhejiang Chaowei Power Supply Co., Ltd. Its model was 6-DZM-20. T. 3.1. Optimal concentration of sulfuric acid for the sulfation of negative lead pastesThe contents of PbO2 and PbSO4 in the negative lead pastes sulfated by different concentrations o. During the desulfurization and crystallization process in NaOH solution after sulfation, the recovery ratio and purity of PbO were 95.72% and 95.31% under the optimal condition. In this paper, a novel method of recovering PbO from lead pastes of spent lead acid batteries by desulfurization and crystallization in NaOH solution after sulfation was pro.