Abstract: The high investment return from financial market often motivates manufacturing enterprises to expand from their main businesses toward financial market in the global scope, resulting in a deepening financial-industrial integration. Based on the non-parametric quantile model for B-spline expansion and the conditional probability density function, this paper draws upon the micro-data of international manufacturing enterprises from 2006 to 2018 to analyze the relevant theoretical mechanism in order to reveal the nonlinear heterogeneous impact of financial-industrial integration on R&D investment. The results show that:(1) The financial-industrial integration of enterprises has the characteristics of convergence between the macro financial development and innovation investment in countries of different type. The impact of financial-industrial integration on R&D investment presents a "U-shaped" promotion effect for developed countries, while the impact for developing countries mainly manifests as an "inverted U-shaped" crowding out effect, and there is an optimal level of financial-industrial integration to enterprise R&D investment. (2) With the improvement of the R&D investment level (corresponding to the improvement of quantile), the inflection point of financial-industrial integration level in developed countries shifts to the left, while that of developing countries shifts to the right, and the intensity of R&D investment is more sensitive to the change of financial-industrial integration level. (3) The financial-industrial integration of medium and high R&D intensive high-tech enterprises mainly shows R&D promotion effect while the medium and low R&D intensive non high-tech enterprises show R&D crowding out effect. According to this research, the financial-industrial integration degree of Chinese enterprises should be adapted to their own R&D investment level and macro financial development, so as to provide decision-making basis for improving the R&D investment goal by selecting a reasonable integration level between industry and finance.

Key words: financial-industrial integration, R&D input, nonlinear heterogeneous effects, nonparametric quantile panel