Abstract: Drilling technology of horizontal well with short frontal didtance from target point has a lot of technical difficulties in the optimization design of wellbore trajectory and prediction of deflecting force of bottom hole assembly, such as the difficulties in predicting the maximum build-up rate and constant curvature very accurately. Analysis has been made against all these difficulties. The key technical point will be focused on the analysis on the influence of frontal distance from the target and build-up rate in wellbore trajectory design on friction torque and the optimization of the prediction method of deflecting force of bottom hole assembly, and the main ideas on the wellbore trajectory design of horizontal well with short frontal distance from the target have been proposed, which means establishing constant curvature-based prediction method of deflecting force of bottom hole assembly with monotone increasing profile by considering such factors as the stabilizer and structure corner, borehole enlargement and bit pressure. The feasibility of relevant key techniques has been demonstrated by combining cases and the prediction method established can effectively guide the requirements for deflecting force of bottom hole assembly when drilling is really made.