The invention provides a cavity phase shifter which comprises a cavity, edge insulators, feeder bases, dielectric plates, a microwave network, a drive pin, and coaxial cables. The drive pin connects the multiple dielectric plates in series. The cavity contains two sub-cavities, and the two inner sidewalls of each sub-cavity are provided with guide slots for fixing the microwave network. One side of the outer sidewall of the cavity is provided with a groove, and the groove is provided with a screw hole and outer sidewall wire holes at positions corresponding to the ports of the microwave network. The middle of the front of each feeder base is provided with a screw fixing hole, and two welding slots are arranged above and below each screw fixing hole respectively. The end of each welding slot is provided with a welding slot wire hole corresponding to the groove of the cavity. The backs of the feeder based are provided with bosses. The fronts of the edge insulators are provided with through holes corresponding to the bosses. The upper and lower sides of each through hole are provided with edge insulator wire holes corresponding to the feeder bases. Through innovative design of the cavity component and the drive pin of the phase shifter, the cavity phase shifter has the characteristics of low cost, low inter-modulation and small size, and is simple in structure, easy to assemble and suitable for mass production.