In the research of scale space fusion of medical big data video image, due to the different spatial management methods of multi-source video image, the efficiency of multi-dimensional scale space fusion is low, so a new image scale space fusion method is designed according to the characteristics of medical big data video image. From the aspect of video image visualization and multi-dimensional space fusion, the space fusion method is designed respectively, and the sampling survey method is adopted for experimental analysis to obtain experimental data. The experimental results show that the proposed method is feasible and reliable.