The 10th Asian-Pacific Conference on Aerospace Technology and Science (APCATS’2019) & The 4th Asian Joint Symposium on Aerospace Engineering (AJSAE’2019) were held jointly during August 28-31, 2019. APCATS being an important technical event in the Asia-Pacific area is convened every two years while AJSAE every year. Both APCATS and AJSAE are important events, which have been devoted to the research and development in all aspects of aerospace technologies and science, in the community of aerospace and aeronautical engineering. These two conferences when jointly held together can become a platform for the delegates from different countries to meet and gain fruitful results.In the joint conference of APCATS’2019 & AJSAE’2019, over 200 experts and researchers in the fields related to aerospace technologies and science attended the conference to share their innovative ideas, discuss the state-of-art methods, exchange their experiences, and establish beneficial collaborations. Delegates from Taiwan, Hong Kong, China, Japan, Korea, Australia, Indonesia, and Philippines enjoyed the good time they had in the conference. There were 102 papers presented orally in the conference and among them 30 papers were selected for publication after peer review. The papers collected for publication are of high quality and related to different areas of aerospace and aeronautical engineering. The conference ended successfully and all the delegates looked forward to attending the next meeting in India in 2021.The success of the joint conference has relied on many people’s efforts and contributions. Many thanks are extended to the colleagues and students of the Mechanical Engineering Department, National Chiao Tung University, for their assistance in organizing the conference. The guidance of the Honorary Co-chairs and Regional Representatives are gratefully appreciated. The reviewers have helped not only review the papers but also provide valuable comments to improve the quality of the papers. Their efforts and assistance are prominent in making the conference a success. Last, but not the least, many thanks to those who have helped chair the sessions, construct the conference website or make arrangements for the conference. The success of the conference is a natural outcome of their contributions and assistance.