This paper reports two investigations on the edge chipping in rotary ultrasonic machining using finite element analysis (FEA). The first FEA investigation establishes a relationship between edge chipping thickness and cutting force. The second FEA investigation is to understand the effects of three parameters (cutting depth, support length, and pre-tightening load) on edge chipping thickness. The investigation results showed that the edge chipping thickness could be reduced by increasing support length and decreasing cutting force.