In order to meet the requirements of real-time monitoring aboutstates of battery group, optimizing control strategy, prolonging battery life and ensuring the safety of use, this paper proposed and implemented a battery pack cloud management system using optimized residual power (SoC) estimation.Based on the traditional SoC estimated strategy (charge accumulating method and open circuit voltage), the extended calman filter algorithm wascombined to improve the accuracy of battery pack’s remaining power estimation, and the mathematical model between the battery voltage and the SoC was established.At the same time, the cloud-server system was added to realize the real-time detection of the battery group. In addition, a battery pack management device with a capacity of 22.2 V was designed and implemented. The experimental results show that the SoC estimation accuracy of the battery management deviceis high, the measurement error is less than 1%, the system stability is good, and the requirements for real-time detection of the battery state are met.