This paper proposes a method to calculate the radar detection coverage with a specific altitude corresponding to one point on the surface， and uses the terrain elevation data to analyze the detection capabilities of 23 new-generation weather radars in Shaanxi and surrounding provinces. Additionally， the paper also does the numerical simulation of the negative elevation angle observation mode and obtains the optimal minimum observation elevation angle of the three mountaintop radars. The results show that the primary and secondary coverage rates of the new-generation weather radar at different altitudes over Shaanxi are：48.6% and 2.3% at 0.5 km， 80.0% and 18.9% at 1 km， 98.7% and 74.5% at 2 km, 99.9% and 97.1% at 3 km and 100% at 4 km height. Considered the 3 X-band weather radars of Shaanxi, the primary and secondary coverage rates are increased to 82.7% and 32.1% respectively at 1 km. On this basis, a method using the average annual rainfall, GDP and population data are suggested to calculate the priority of radar coverage in blind areas and counties in Shaanxi Province. The findings of this study could provide a theoretical and technical support for the building of weather radar in the blind area of radar coverage in the future.