Using sounding rocket data, a new generation of weather radar data and meteorological data to comprehensively analyze the hail cloud in Baota District, Yan"an County on July 17, 2015. The results show: (1)At BT 08:00 am, low vortex in Hetao Region split eastward, with a strong cold advection, moving fast and a rising of surface temperature at BT 14:00 pm caused this hail. (2) The hailstorm conditions inside the backward position, such as temperature and humidity ,Tg convection index, IQ whole layer special humidity integral, TT（Totals totals index）are smaller than that in external natural atmosphere. The stratification stability, expressed by K index, LI（lifted index ）and SI（Showalter index ）show that hail clouds are smaller inside than outside. The thermal parameter SSI（Storms Severity Index） in the hail cloud is lower than that in natural atmosphere. The internal energy parameter CAPE（Convective Available Potential Energy）and Vm（maximum updraft velocity） in the hail cloud are significantly lower than that in natural atmosphere. The 0℃ layer height in the hail cloud is not so high as that in natural atmosphere. The - 20 ℃ high temperature layer, air flow is stronger, the whole layer partial sinking airflow. (3) Location of the rocket detection is opposite to the back of the hail cloud. The wind direction changes counterclockwise from the down to the up in hail cloud. (4)The temperature range which is near the 0℃ layer in hail cloud is 5.0℃--1.8℃. The maximum humidity area is within the depth of 1.0km, where humidity is over 80% and the maximum humidity is 87.1%. These provide water vapor conditions for the formation of hail. (5)There is a maximum horizontal wind speed of 19 m·s-1 rapid flow and thickness of 0.022 km close to the lower layer of 0℃.It is also maintain a horizontal wind speed of 13 m·s-1 or above in the temperature range of 5.0--4.8℃ and a thickness within 1.6km. These provide a dynamic field condition for the formation of hail.(6)There is a weak wind zone of ≤2 m·s-1 in areas where temperature range is -8.7--9.2℃ and the thickness is in 0.2km. Below the weak wind zone, where temperature range is -4.6--8.8℃ and the thickness is in 0.889km, it is updraft. In this place, the average rising speed is 1.79 m·s-1 and the maximum rising speed of 4 m·s-1. This configuration provides an environmental field for the growth of hail.