A reliability based keyframe switching system adaptable to iterative closest point (ICP) includes a camera that captures frames; a matching device that determines corresponding pairing between the frames for an ICP operation to form a set of plural point-pairs; a transformation device that performs transformation estimation to estimate transformation that minimizes distances of the point-pairs, and determines whether the estimated transformation converges; and a reliability device that determines whether the ICP operation is reliable, and replaces a current keyframe with a new keyframe if the ICP operation is determined to be unreliable.