Embodiments of the invention disclose a data storage method. The method comprises the following steps of: when the fact that a power end of a universal serial bus USB interface of a terminal is in short circuit with a differential signal end is detected, obtaining a differential voltage value of the differential signal end; if the differential voltage value is greater than a first preset voltage threshold value, obtaining data, in transmission state, of a USB data channel; and storing the data. The embodiments of the invention furthermore disclose a data storage device. By adoption of the data storage method and device, the transmitted data can be stored in time when the differential voltage value at the USB interface of the terminal is too high, so that the loss of the transmitted data is prevented and the data transmission efficiency is improved.