A platform service system for integrated battery management, comprising: (a) a data management module configured to collect battery characteristic data of an electric vehicle through a network and accumulatively store the battery characteristic data in a battery characteristic data database, DB, to be matched with a battery identification code; (b) a State of Health, SOH, management module configured to calculate a SOH, which is a current SOH of a battery, by analyzing the battery characteristic data and store the SOH in a SOH history DB to be matched with the battery identification code; (c) a reuse grade management module configured to inquire the SOH history DB using the battery identification code to determine a current SOH when a reuse grade calculation request is received from a client through the network along with the battery identification code, determine a reuse grade corresponding to the current SOH with reference to predefined reuse grade information for each SOH and store the reuse grade in a reuse grade management DB, and transmit the information about the reuse grade to the client; and (d) a reuse tracking management module configured to receive a reuse approval message for the battery from the client through the network, transmit battery reuse information containing the battery identification code of a reuse-approved battery to a reuse company management system through the network, and store a battery identification code contained in a battery warehousing certification message in a reuse tracking management DB to be matched with an identification code of a reuse company when the battery warehousing certification message containing the battery identification code of a reuse battery is received from the reuse company management system. (a) a data management module configured to collect battery characteristic data of an electric vehicle through a network and accumulatively store the battery characteristic data in a battery characteristic data database, DB, to be matched with a battery identification code; (b) a State of Health, SOH, management module configured to calculate a SOH, which is a current SOH of a battery, by analyzing the battery characteristic data and store the SOH in a SOH history DB to be matched with the battery identification code; (c) a reuse grade management module configured to inquire the SOH history DB using the battery identification code to determine a current SOH when a reuse grade calculation request is received from a client through the network along with the battery identification code, determine a reuse grade corresponding to the current SOH with reference to predefined reuse grade information for each SOH and store the reuse grade in a reuse grade management DB, and transmit the information about the reuse grade to the client; and (d) a reuse tracking management module configured to receive a reuse approval message for the battery from the client through the network, transmit battery reuse information containing the battery identification code of a reuse-approved battery to a reuse company management system through the network, and store a battery identification code contained in a battery warehousing certification message in a reuse tracking management DB to be matched with an identification code of a reuse company when the battery warehousing certification message containing the battery identification code of a reuse battery is received from the reuse company management system.