An information reminding method during the prevention of oil theft, and an alarm system. The method comprises: recording the height of oil in an oil tank of a user vehicle when the vehicle is parked (S101); monitoring whether the height of the oil in the oil tank of the user vehicle has dropped (S102); if not, maintaining the original state (S103); if so, detecting whether an engine of the user vehicle is started (S104); if so, maintaining the original state (S105); and if not, automatically initiating an alarm to remind a user of same, and pushing patent information to the user at the same time (S106). According to the method, in the case where a vehicle is not started, a system detects a change in the height of oil in an oil tank, so as to actively send an alarm to a user, thereby preventing fuel oil from being stolen, avoiding huge economic losses for the user, and protecting the benefits of patentees (applicants) at the same time.
