Abstract: Downbursts are extreme winds that are small in scale, short in duration, and severe in destruction. The wind fields have three-dimensional characteristics and significant non-stationary properties, with key wind field parameters evolving over time. In order to study the spatiotemporal evolution characteristics of downburst wind fields, a typical thunderstorm outflow record was identified and obtained by the grounds of the field measurement data collected by the Beijing 325 m meteorological tower, and the evolutionary characteristics of the time-varying mean and fluctuating winds were studied, including the correlation of wind speed along height, the evolution of the time-varying mean wind speed profile and turbulence intensity profile, and the evolutionary power spectral density of the residual fluctuating wind speed. Additionally, key wind field parameters such as turbulence integral scale and power spectrum were also analyzed. The research findings indicate that: the cross-correlation coefficients of the time-varying average wind speed at different heights span from approximately 0.6 to 0.9, denoting a robust correlation, whereas the residual fluctuation has almost no correlation at different heights. The time-varying mean wind speed profile exhibits a distinctive "nose-shaped" profile at the instant of peak wind speed, showing patterns similar to those of large-scale synoptic winds before and after the downburst. The turbulence intensity is markedly higher near the ground compared to aloft, peaking at 0.3. The measured power spectrum of downburst is in a good agreement with the Von Karman spectrum. The turbulence integral scales are determined to be between 9.5 m and 29.4 m, considerably smaller than those for large-scale synoptic winds. The residual fluctuating wind speeds present pronounced non-stationary characteristics in both the time and frequency domain, with energy predominantly distributed during periods of rapid wind speed transitions in the time domain, and mainly concentrated around 0 Hz to 0.1 Hz in the frequency domain.