This paper uses quantiles regression and OLS to research on foreign and domestics manufacturers in China, analyzing the effect of firm size and R&D on export intensity. Different from previous literatures, this paper points out and verifies three hypothesizes: (1) the relationship between firm size and export intensity will be different from difference between export tendency and ownership. (2) R&D and export intensity are negatively correlated. (3) R&D spillovers should be beneficial to firms’ sales in domestic market, but the degree is related to export tendency and ownership.