The Weihe fault is a large fault which traverses the central section of the Weihe basin. It controls the formation and growth of the Weihe basin, as well as the seismic activity in the basin. Taking the west section of the Weihe fault stretching from the Baoji Gorge to Caotan Village of Xi'an city as a study area, this paper analyzes and discusses the activity difference of the west section of the Weihe fault based on the grading phenomenon of the loess platform geomorphology on the north side of the Weihe fault, uneven changes of fault displacement of the Tertiary system from west to east, and geographic difference of the steep faulting slope along the west section of the Weihe fault. It is considered that the west section of the Weihe fault can be divided into three sub-sections : the eastern, middle and western ones, and they are different distinctly in fault active period and active strength. Through the analysis of the Neotectonic environment of the west section of the Weihe fault, this paper also considers that the crust tilting movement characterized by eastward upwarping in the west part of the Weihe basin since Quaternary is the main cause of the activity difference of the west section of the Weihe fault.