A method and an apparatus for switching an ECG measurement mode, a wearable device, and a computer-readable storage medium. The method includes: receiving two successive pieces of PPG data transmitted by an optical heart-rate sensor, where the PPG data is generated by a contact between a measurement electrode and a skin; calculating a difference between the two received pieces of the PPG data; and controlling switching among measurement modes based on the difference, where the measurement modes comprise an ECG wristband mode and an ECG chest-lead mode Manual switching of an ECG measurement mode is avoided with simple operations, high efficiency, and more intelligence.