I selected a model and use "Origin to Geometry" to set origin. As a result, the yellow point move to the head part of model, instead of the model's center.
So it's clear that blender default the geometry center based on the volume of the mesh. On my case, there are more meshes on the head of model.

Image reference: How to recenter an object's origin?
If I use "Origin to Center of Mass (volumn)", the yellow point will be on the center of course.
But if my project requires that I must use "Origin to Geometry", how can I let the point on the center of model?
