Carbon fiber reinforced plastics (CFRP) and alloy stacked materials are used in the manufacturing process in the fields of aerospace. And the CFRP/Ti stacked material is widely used. The processing defects caused by heat are more significant in the drilling of CFRP/Ti stacked material, and mostly appear at the interface where two materials are in contact. Therefore, the main factors affecting the interface temperature in drilling of CFRP/Ti stacks are studied. The experiment of the interface temperature monitoring in the drilling of CFRP/Ti stacks with the help of thermocouples is designed. The processing parameters and ultrasonic assistance parameters were changed in the experiment. The primary object of this study is investigating the relationship between processing parameters and interface temperature in the variable parameters drilling of CFRP/Ti stacks, and the influence of the ultrasonic is also discussed.