Abstract: Abstract: R&D innovation is considered an effective means to address climate change. The Beijing-Tianjin-Hebei urban agglomeration plays a critical leading and exemplary role in promoting R&D innovation and reducing regional carbon emissions, especially with industrial enterprises playing a dominant role in R&D innovation. Based on panel data from industrial enterprises in various prefecture-level cities in the Beijing-Tianjin-Hebei urban agglomeration from 2010 to 2020, this study decomposes R&D innovation into two dimensions: efficiency and scale. Through indicator measurement, econometric modeling, and spatiotemporal analysis, this paper empirically investigates the spatiotemporal impact of R&D innovation by industrial enterprises on carbon emission intensity in the Beijing-Tianjin-Hebei urban agglomeration. The research results show that: (1) There are significant differences between R&D scale and innovation efficiency. During the study period, the R&D scale of industrial enterprises in various regions steadily increased, while innovation efficiency fluctuated relatively. (2) The spatial impact of R&D innovation on carbon emission intensity exhibits a two-stage characteristic, with 2016 being the most significant turning point, shifting the significant spatial weight matrix from geographical distance to economic distance. (3) From the scale dimension, there is a time lag effect in reducing carbon emission intensity by expanding the R&D scale. (4) From the efficiency dimension, the short-term impact of innovation efficiency on carbon emission intensity is not obvious; long-term accumulation is required to effectively reduce carbon emission intensity. The study innovatively analyzes the spatiotemporal impact of R&D innovation on carbon emission intensity of industrial enterprises in the Beijing-Tianjin-Hebei urban agglomeration from both scale and efficiency dimensions, exploring their differentiated impact paths. The research results will provide important references for the rational layout of R&D scale and efficiency within China's urban agglomerations and promote regional collaborative carbon reduction.