Wellbore trajectory system is a complicated nonlinear system. Cost-effective solution for wellbore trajectory control is essential. For the nonlinear characteristics, since the nonlinear control theory is not mature, and the method is also more complicated, fuzzy control method plays a major role and becomes a reliable way to resolve the control problem of nonlinear system. The main advantage of fuzzy control lies in the capacity for ignoring the inaccuracy and going without the precise mathematic model, and it is very often used for analyzing the performances of nonlinear system, and optimizing ultimate result. Aiming to complicated dowhole conditions and the uncertainty of downhole affecting factors, fuzzy control theory is applied to analyze downhole control problems. Combining the fuzzy control theory with drilling engineering problems, the downhole fuzzy controller was designed. This article highlights the design process for wellbore trajectory fuzzy controller and formation of control rule-base. As an effective simulation tool, visually dynamic simulation and system modeling for wellbore trajectory control can be realized using matlab.