The purpose of the study is to examine how effects of activities using Google SketchUp on students` spatial ability and 3D geometric thinking in measuring the volume of solid figures. By comparing the results from pre- and post-tests between the experimental group and control group, we found that activities using Google SketchUp help students improve their spatial ability in the spatial orientation and visualization. In addition,more than half students in the experimental group moved from level 4 up to level 7 in thinking process of measuring the volume in terms of Battista(2004)`s levels. This study suggests that the instruction with Google SketchUp can help to improve students` spatial ability and 3D geometric thinking in the regular class in middle school. In addition, SketchUp can be an advanced technological tool to support students` self-directed learning, which create an efficient educational environment and a great opportunity to learn geometry in an effective manner.