The ultimate goal and destination of the public domain of intellectual property should be to encourage innovation and expand public civilization space for mankind. From Enlightenment age to the Internet age, intellectual property rights came from the public domain and ultimately reversed to public domain. The theories, including Aristotle’s theory of deontology and consequences and Locke’s labor theory as well as Kant’s theory of natural rights, all believes that intellectual property rights are equally important in the public domain. Public domain resources are the source of innovation. Especially with the new technology in the digital age, the utilization of the public domain has gradually shifted from the traditional negative model to the positive utilization model. However, current intellectual property regime has been criticized to be a kind of protectionism against innovation. It is necessary to develop public domain to promote new innovations. A robust public domain system shall be determinable, available, sustainable, non-excludable and noncompetitive. The key to the "good law" of IPR lies in finding a balance between the private IPR and the public domain. The expansion of exclusive rights should be prudent and modest. At the same time, it is noted the significance of strong public sphere in a knowledge-based economy to promote common progress and enhance benefit for all.