This paper studies the 3D interaction performance and user experience evaluation of the virtual 3D object in the mixed reality sand table, and puts forward interaction design principles and design suggestions. The interaction design is carried out for the "selection" task of virtual objects outside the touchable range of both hands in the mixed reality environment. The layout mode of virtual objects is creatively introduced as an evaluation variable. And under the three typical virtual object layouts, a comparative study on the performance and user experience of three interactive modes of hand-controlled light, head movement, eye movement and gesture coordination is carried out. Through the design of an experimental prototype system, user experience test, experimental data analysis and evaluation, we verify the principles of interactive design, and put forward interactive design suggestions. The experimental results show that the hand-eye collaborative interaction mode combined with gaze and pinch gesture has significant advantages in time, task load and user preference. The accuracy of point and pinch interaction is the best in all the three layouts. It is suggested that the design of "selection" task interaction in the mixed reality environment should pay attention to the principles of functionality, continuity and pleasure, and put forward some design suggestions to reduce the work load and fatigue of "selection" task interaction and adopt novel interaction to improve pleasure.