Abstract: To satisfy the requirements for millimeter-wave reconfigurable communication systems, we designed a millimeter-wave reconfigurable Wilkinson power divider. At first, we designed an S band reconfigurable Wilkinson power divider based on PIN diode, and then the design principle was used in K/Ka band. We studied the effects of the parasitic parameters of PIN diode and the best matching method with parameter extracting, and designed a K/Ka band reconfigurable power divider. We conducted simulation and measurement, and the measurement results show that in the working band, in two-way mode the insertion loss from port 1 to transmission ports (port 2 and port 3) is below 4.92 dB and the isolation between two transmission ports is above 15.8 dB; in one-way mode the insertion loss is below 1.65 dB and the isolation between port 1 and the isolation port is above 22.4 dB. The measurement and simulation results generally agree with each other. Considering the effects of the parasitic parameters of PIN diode, and using EM/circuit co-simulation, we designed a reconfigurable power divider based on PIN diode in K/ Ka band with is accurate, simple and suitable for applications in reconfigurable systems.