The construction of well-facilitated capital farmland is not only a national institutional arrangement but also a technological activity，and the technological progress in terms of factors is the essence of the well-facilitated capital farmland construction. This paper establishes a theoretical analysis framework of “institution+technology——grain productivity” and uses the continuous DID model to analyze the impact and mechanism of the implementation of well-facilitated capital farmland construction policy on grain productivity.The findings are as follows.Firstly，the implementation of well-facilitated capital farmland construction policy significantly improved the grain productivity，and the results remained significant through a series of robustness tests. Secondly，the heterogeneity analysis showed that the implementation of well-facilitated capital farmland construction policy has a higher marginal contribution to the improvement of grain productivity in non-major grain producing areas and mountainous areas compared with major grain producing areas and plain areas.The policy had a positive impact on both the quantity and quality of grain，with a more pronounced effect on promoting grain quality.The policy also promoted the increase of grain quantity in major grain producing areas and the improvement of grain quality in non-major grain producing areas，as well as the increase of grain quantity in plain areas and the double improvement of grain quantity and quality in mountainous areas.Thirdly，mechanism analysis showed that the implementation of well-facilitated capital farmland construction policy improved grain productivity by optimizing the allocation of production factors and promoting agricultural scale operation.This study provides a new perspective for understanding grain productivity，and also offers a new idea for promoting grain production capacity through the construction of well-facilitated capital farmland.