Against the backdrop that the “Double Reduction” policy driving the structural transformation of basic education, as an important carrier of non-formal science education, science and technology museums have gradually become embedded in the after-school service systems of primary and secondary schools, becoming an integral component of the collaborative supply of educational resources. Based on a review of relevant policy documents and an analysis of typical cases, this paper systematically analyzes the science education service capabilities and operating mechanisms of science and technology museums during the implementation of the “Double Reduction” policy series from the dimensions of resource integration, content innovation, teacher support, organizational collaboration, and digital empowerment. The study indicates that science and technology museums have demonstrated strong practical responsiveness in promoting the integration of educational resources, optimizing the supply of science courses, supporting teachers’ professional development, and expanding digital education scenarios. Meanwhile, science and technology museums are also confronted with such challenges as insufficient depth of institutional embedding with blurred responsibility boundaries, fragmented coordination mechanisms with low efficiency in multi-party cooperation, and unbalanced resource and capability support alongside a weak digital foundation. Based on these findings, this paper proposes countermeasures to enhance the science education capacities of science and technology museums, including improving institutional supply to deepen their participation in the “Double Reduction” policy, reconstructing collaborative architectures to boost the governance efficacy of multi-party cooperation, and establishing a sound multi-faceted support system to consolidate the digital foundation. These measures aim to provide a theoretical basis and practical reference for expanding the science education functions of science and technology museums and ensuring the high-quality implementation of the “Double Reduction” policy.