Understanding the behavior of soil wetted volume evolution in drip irrigation is essential for improving agricultural water use efficiency and realizing precision irrigation. Based on the Richard equation for water movement in unsaturated soil, the HYDRUS-2D/3D model was used to numerically simulate the soil wetting pattern in 11 kinds of typical soils (USST). Results showed that soil water content increment in wetted volume was in a positive correlation with the dripper discharge rate, and in a negative correlation with the saturated soil hydraulic conductivity. The advancement of vertical wetting front can be quantified by the selected influencing factors, i.e., the dripper discharge, saturated hydraulic conductivity and irrigation time. The horizontal wetting front can be expressed by the dripper discharge, soil water content increment in wetted volume, vertical wetting front and irrigation time. Then two empirical equations were formulated to describe the development of soil wetted volume under different dripper discharge, saturated hydraulic conductivity and irrigation time. By comparing with the numerical simulation results and the experimental data from literatures, it showed that the empirical formulas were reliable for predicting the migration of soil water in drip irrigation for different kinds of soil textures and managing to be a convenient and practical tool for the design of surface drip irrigation in agricultural activity.