In comparison to the acquisition of total electron content data using global navigation satellite systems, traditional ionospheric sounding data in the form of vertical and oblique sounding at shortwave bands offer distinct advantages, including rich characteristic parameters, high spatial resolution, and extensive historical data. In order to study the ionospheric disturbance caused by underground nuclear explosions using vertical and oblique ionospheric data. The ionospheric disturbance phenomena were analyzed using the oblique and vertical data of North Korea 's underground nuclear test on January 6, 2016. The results indicate that the ionospheric disturbance caused by the underground nuclear explosion is characterized as a small-scale disturbance, with a propagation speed ranging between 150.3 and 158.7 m/s. Additionally, half an hour after the nuclear explosion at a distance of 421.4 km from the epicenter, an increase of 0.7 MHz in foF₂ was observed compared to the monthly median. Furthermore, compared to January 5 and January 7 foF₂ values at 2:00 UTC, an increase of 0.5 MHz is recorded. This is highly likely attributed to the increase in ionospheric electron density caused by the underground nuclear explosion through the lithosphere-atmosphere-ionosphere coupling mechanism. The analytical results of this study align closely with other literature, affirming that the detection of ionospheric disturbances using shortwave ionospheric sensing is an effective means for monitoring underground nuclear explosions. This method can complement other direct monitoring approaches, thereby enhancing the capability for detecting nuclear explosion events.