For the needs of modern communication and phased-array radar applications, a Ka-band 4-bit switched-line RF MEMS phase shifter with a phase shift interval of 22.5° was developed. The four phase shifting units, which primarily realized the phase shifting function, were designed to provide the best impedance matching by optimizing the division of the upper and lower paths of the phase shifting units to select the pass by using the step compensation technique. Using a right angle corner structure, a delay line that improved the performance of the CPW right angle was designed, and a general design of a 4-bit switched-line phase shifter applied with this delay line was presented. Modeling and simulating with HFSS showed that the insertion loss of all 16 states was less than 2.15 dB, the return loss was greater than 19.18 dB, the VSWR was less than 1.25, the phase shift error at 40 GHz was within 1.57°, and the overall size was 10 mm2 in the 0~40 GHz operating band.