The state of charge (SOC) of the battery is a crucial aspect in ensuring the safe charging of Automated Guided Vehicles (AGVs). However, with battery aging, it becomes challenging for the Battery Management System (BMS) to maintain the accuracy of SOC data, leading to overcharging during the charging process. To address this issue, a SOC estimation method based on DBN-ELM for AGVs is proposed, along with the use of an improved dynamic simplified particle swarm optimization to overcome the issue of manually setting parameters in traditional DBN. Furthermore, for addressing missing data during the charging process, bidirectional LSSVM is utilized for data completion. Experimental results demonstrate that this method effectively enhances the SOC prediction accuracy of AGVs and holds practical significance.