Opening-up and economic security are important relationships that must be well balanced in the new era. This paper uses the SV-TVP-SVAR model to dynamically identify the time-varying and temporal impacts among opening up to the outside world, financial stability, and high-quality economic development, and details the economic and financial effects of different opening modes. The research shows that different forms of openness have heterogeneous impacts on high-quality economic development and financial stability. Trade openness can significantly promote high-quality economic development in the short and medium term, while investment openness has a positive and negative alternating effect on high-quality economic development in the short term, and a certain positive effect in the medium term. The long-term effect mechanisms of both openness modes are unclear. There are significant differences in the impact of trade openness and investment openness on financial stability, and the role of financial stability in the transmission channels of opening up to the outside world has not been effectively played. Therefore, efforts should be made to improve the level and quality of opening up to the outside world, coordinate high-quality development and high-level security to help China’s economy and finance to achieve stability and long-term development.