Theoretically, weak Porter Hypothesis involves dual externalities including negative externality of pollution and positive externality of scientific and technological innovation. Environmental regulation should be combined with protection of intellectual property to completely solve the dual externalities, but the protection of intellectual property has not been paid enough attention in practice. Taking SO2 emission abatement technology as an example, this paper collects provincial data during 2000-2013, and adopts fixed effect model to examine the effect of intellectual property protection on weak Porter Hypothesis. The results show that when intellectual property protection is weak, environmental regulation has a negative impact on innovation in atmospheric science and technology. When intellectual property protection level exceeds a certain threshold, environmental regulation begins to have a positive impact on the innovation, and weak Porter Hypothesis is established. Moreover, cross effect of environmental regulation and intellectual property protection on the innovation commonly appears in firms rather than universities or individuals.