The utility model belongs to the technical field of electronic technology and weather forecasting and relates to a thunderstorm approach forecasting device. The device consists of a direct-current power supply, a power supply filtering circuit, a direct-current coupling self excited oscillation circuit and a rectifying and amplifying circuit, and is characterized in that: an antenna (T) is connected into the direct-current coupling self excited oscillation circuit; and a load in the rectifying and amplifying circuit is a piezoelectric ceramic buzzer (HA). The device is an acousto-optic electronic forecasting device which can forecast thunderstorm before the thunderstorm approaches. Discharge between cloud layers in remote sky or between a cloud layer and the ground can be detected through the device. Corresponding lightning stroke-preventing measures can be timely and quickly taken through the thunderstorm approach forecasting, and thus accidents are effectively prevented.