At present piperoof advance reinforcement is widely used in the construction of tunnels in soft ground. On basis of the difficulties in the drilling of the horizontal boreholes in soft ground, the author analyzes on the three factors that may result in deflection of boreholes, expatiates on the borehole drilling technology for the piperoof reinforcement of shallowburied tunnels in soft ground and provides the methods for the measurement, prevention and correction of the inclinations of the horizontal boreholes. Taking the construction of the piperoof reinforcement of the ZhuGu running tunnel of Nanjing Metro as example, the author also presents the results of the cased auger boring of the horizontal boreholes.