A measuring device of cavity type parts and a measuring method thereof relate to a measuring device of cavity type parts, in particular to measuring device which measures actual numerical values of a distance between a bottom plane of a cavity and a hole on an outer lateral surface of the cavity. The measuring device of cavity type parts comprises a positioning block, a transition plate, a dialgauge, a pin boss, guide columns and a conical pin, the upper end surface of the positioning block is connected with the pin boss through the transition plate, the positioning block is connected with the transition plate via bolts, the upper end surface of the pin boss is equipped with the dialgauge, the lower end of the pin boss is connected with the two guide columns which are arranged in parallel, and the lower end surface of the pin boss is equipped with the conical pin. The invention realizes the purpose of field control tracking and convenient and simple measurement.