In view of the SOC jump occurring at the charging ending and the beginning of the discharge during the charging and discharging process of the electric forklift, based on the traditional ampere-time integration method and combined with open-circuit voltage method, an exploration has been made into the internal relationship between open-circuit voltage and SOC. With the maximum voltage and minimum voltage fusion algorithm combined, a proposal has been made of two SOC smooth display schemes, which are modeled and simulated by Simulink. The simulation results are observed to determine the optimal scheme, which will be implemented in the electric forklift truck, with a SOC accuracy test to be carried out according to Technical Conditions of Battery Management System for Electric Vehicles (QC/T 897—2011). The test results show that, under the optimal scheme, SOC does not experience any jump during the whole charging and discharging process, where the estimation accuracy is 1.30% with SOC no less than 80%, and 2.42% with SOC no more than 30%.