The invention relates to an intelligent impromptu preliminary budget realization method for power distribution network engineering. The method comprises steps that an engineering equipment account reserve bank is constructed; a graphical element model database is established; a preliminary budget standard type database is constructed; power distribution network engineering preliminary budget results are determined according to a power distribution network engineering wiring diagram, the engineering equipment account, a graphical element model and preliminary budget standards; the power distribution network engineering preliminary budget results are presented in an impromptu mode. The method is advantaged in that engineering preliminary budget quality and efficiency are substantially improved.