A method for monitoring physiological status of a vehicle driver is performed by a monitoring device connected to a physiological sensor and comprises steps of: (a) establishing a personal physiological database comprising steps of: periodically sensing the vehicle driver via the physiological sensor to obtain the physiological signals within an initial duration; obtaining a mean value and a standard deviation based on the physiological signals; and obtaining a tolerance range based on the mean value and the standard deviation, such that the personal physiological database stores the tolerance range; (b) sensing the vehicle driver via the physiological sensor to obtain at least one instant physiological signal after the initial duration; and (c) determining whether the at least one instant physiological signal is out of the tolerance range, such that an alarm is outputted when the at least one instant physiological signal is out of the tolerance range.