Abstract: A gateway in a steep inclined seam was affected by the geological conditions,gateway sectional sharp and other factors and the loosing circle developm ent in the surrounding rock of the gateway was in unbalance and would be serious effected to the stability of the gateway.The electromagnetic wave technology of the g eological radar was applied to measure the loosing circles in the surrounding rock of the mining gateway in the steep inclined seam of Zhaojiaba Mine.With the analysis on the wave profile figural of the radar,the scope of the loosing circle in the surrounding rock was obtained.The results showed the loosing circle of the cross section at the different measuring station in the gateway in the steep inclined seam would be different and the loosing circle scope of the cross section at different location of the s ame measuring station would be different too.According to deformation features of the site gateway and the measured results of the loosing circle in the surrounding roc k,the cross section profile adjusted of the gateway could form a arch stable structure at high expanded side of the loosing circle in order to release the stress concentra tion and to have the stability control of the surrounding rock in the gateway.