The invention relates to a method and device for measuring the battery performance. The method includes: performing floating charge treatment on a battery to obtain a battery after the floating charge; performing activation treatment on the battery after the floating charge to obtain an activated battery and measuring the discharge capacity of the battery during the activation process; carrying out floating charge treatment on the activated battery and measuring the charge capacity of the battery during the floating charge treatment; and acquiring performance information of the battery based on the discharge capacity and charge capacity of the battery. According to the provided method, the floating charge treatment is performed on the battery, so that the battery reaches a float charging state; and the battery after the floating charge is activated to obtain the maximum discharge capacity of the battery accurately. Because of the floating charge treatment on the activated battery, thecharge remaining interference of the battery is prevented to obtain he maximum charging capacity of the battery, so that the performance information of the battery can be accurately obtained.