The use of a waveguide perpendicular to boundaries of the microdisk cavity is a newly developed coupling technique. We make a detailed analysis about the adaptation of the cavity size, the adaptation of the wavelength and the expansibility of the ports. The results confirm that the perpendicular coupler is valid in large cavity or multiple bands. It is shown that multiple perpendicular couplers can exchange energy with a microdisk cavity and work as filter, beam splitter, and crossroads of optical path. The usage of perpendicular coupler in integrated optical circuit with microcavity components will make the selection of materials and arrangement of the optical path more flexible.