Using the data of the industrial enterprises in Beijing，this paper tested the threshold effect of government funding on private industrial R&D investment and analyzed the influence of four factors on the incentive effect. The results illustrated the government founding on private industrial R&D investment has significant threshold effect which sensitive to the funding intensity，enterprises size and property right. From the perspective of enterprises R&D investment，government should control the intensity of R&D subsidies within 9%. And it is more effective for the funding of the larger enterprises or state-owned enterprises.