A wrist-worn device and a blood pressure measuring method based on the same are disclosed. The wrist-worn device comprises a main body and a wrist band connected to the main body, and further comprises: a photoelectric tube located on a back surface of the main body and configured to collect pulse data of a wearer; electrodes configured to collect electrocardiograph data of the wearer, an insulator located between two of the electrodes, for preventing both from a direct electrical connection; a circuit board electrically connecting the photoelectric tube and the electrodes, the circuit board calculating a blood pressure value based on the collected pulse data and the electrocardiograph data.