The invention discloses a service type detection method and a service type detection device, and belongs to the field of satellite mobile communication. The method comprises the following steps of acquiring first message information in first service data if a service type corresponding to message header information is not found, and acquiring the second message information of second service data of a service type detected within a preset time period before current time; calculating first similarity between the first message information and each piece of second message information, and judging the minimum first similarity is more than or equal to preset similarity or not; if the maximum first similarity is more than or equal to the preset similarity, determining the service type of the second service data corresponding to the second message information corresponding to the maximum first similarity as the service type of the first service data. According to the method and the device, calculation for the detection of the service type in other ways when the service type is not detected in the message header information of the service data is reduced, so that the service type detection efficiency is improved.