High-frequency (HF) ground wave radar's over-the-horizon property can effectively overcome the restraints posed by the curvature of the earth. HF radar transmits low-power radar waves and its detection distance is up to several hundred kilometers. However, radar in HF bands may be easily contaminated by noise, which has temporal and spatial variability, and ionospheric interference, limiting system performance. Therefore, understanding the regional properties of noise environmental is critical. This study investigates the spatialoral properties of noise in long-term radar data and then analyzes the relation between noise and ionospheric indices. A comparison of the time series of ionosphere and noise indices indicates a diurnal fluctuation property. These results through cross correlation show the consistency of SUAO and HABN HF radar sites and a dramatic change of correlation coefficients over time delay. Most of the strongest negative correlations at both radar sites were found with lead time of noise index about time delay between 2 to 4 h during test period.