The pickup of 3D model is importantly applied in terms of 3D human-computer interaction, and the graphics pickup of interactive graphics system. Currently, the picking algorithm must count on mouse. There are a series of inverse matrix problems in the process of picking algorithm, such as too much simple pickup-surrounded of the structure of 3D model, which influence the effectiveness, convenience and veracity of pickup. A 3D model packing algorithm is presented based on spatial orientation vector and bounding volume strategy. Firstly, spatial attitude information of interactive pen is solved in the slave computer space using entity interactive pen instead of a mouse, then map it into the virtual scene space to make a pick-ray. Secondly, adopt the strategy of shape determination threshold, for 3D model, according to the shape characteristics of different modules, which establish box-shaped bounding and spherical bounding real-time. At last, we judge if it pickup the specific modules or not through the intersection detection between pick-ray and specific bounding. We make specific 3D Model as an example in our experiment, with the using of this algorithm which is pointed out in this paper, the rate of pickup rises 16.98%. What’s more, the pickup misdiagnosis rate of module edges of 3D model is lowed down to 12.80% from 71.26% when it uses the single bounding. The operation is effective and convenience.