The invention discloses a miniaturization design method of a low-frequency micro-strip power divider and a coupling bridge. The method includes the following steps that parameters of high resistance or low resistance micro-strip lines in the low-frequency micro-strip power divider and the coupling bridge are extracted; the high resistance or low resistance micro-strip lines in the low-frequency micro-strip power divider and the coupling bridge are replaced by special micro-strip structures formed by interdigital capacitors, the high resistance micro-strip lines and port matching micro-strip lines; the extracted phase parameters are divided by phase characteristics of the special micro-strip structures, and then it is determined that which level of the special micro-strip structures are used; the determined one-level or multi-level special micro-strip structures are connected in a cascade mode and used for replacing the original high resistance or low resistance micro-strip lines, and then the novel miniaturized micro-strip power divider and the novel coupling bridge are obtained. The method is suitable for the miniaturization design of the low-frequency micro-strip power divider and the coupling bridge.