Due to recent pandemic, the 2021 4th International Conference on Civil, Architecture and Environment Research (ICCAER 2021) which was planned to be held in Zhuhai, China, was held virtually online during January 15-17, 2021. The decision to hold the virtual conference was made in compliance with many restrictions and regulations that were imposed by countries around the globe. Such restrictions were made to minimize the risk of people contracting or spreading the COVID-19 through physical contact. There were 90 individuals who attended this on-line conference, represented many countries including Malaysia, Singapore and China.ICCAER 2021 was hosted by AEIC Academic Exchange Information Center, supported by Guizhou Minzu University. ICCAER 2021 is to bring together innovative academics and industrial experts in the field of civil, architecture and environment research to a common forum. The primary goal of the conference is to promote research and developmental activities in civil, architecture, environment research and another goal is to promote scientific information interchange between researchers, developers, engineers, students, and practitioners working all around the world. The conference will be held every year to make it an ideal platform for people to share views and experiences in civil, architecture and environment research and related areas.During the conference, the conference model was divided into three sessions, including oral presentations, keynote speeches, and online Q&A discussion. In the first part, some scholars, whose submissions were selected as the excellent papers, were given about 5-10 minutes to perform their oral presentations one by one. Then in the second part, keynote speakers were each allocated 30-45 minutes to hold their speeches. In the second part, we invited four professors as our keynote speakers. Assoc. Prof. Yang Wu, from Guangzhou University, China, performed a speech: Experimental investigation on mechanical behavior and particle crushing of calcareous sand retrieved from South China Sea. And then we had Prof. Dongfang Yang from Guizhou Minzu University, China. His research area: Quantitative preliminary study on the growth process of phytoplankton in Jiaozhou Bay. The others keynote speakers were as list: Prof. Xiuxin Wang, from Southeast university, China; Prof. Hongfu Zhou, from Shandong University of Science and Technology, China. Their insightful speeches had triggered heated discussion in the third session of the conference. Every participant praised this conference for disseminating useful and insightful knowledge.The proceedings are a compilation of the accepted papers and represent an interesting outcome of the conference. Topics include but are not limited to the following areas: Disaster Prevention and Mitigation, Renewable Sources of Energy-energy Savings, Garbage classification, Satellite Applications in the Environment, Waste Minimization and more related topics of environment. All the papers have been through rigorous review and process to meet the requirements of International publication standard.We would like to acknowledge all of those who supported ICCAER 2021. The help and contribution of each individual and institution was instrumental in the success of the conference. In particular, we would like to thank the organizing committee for its valuable inputs in shaping the conference program and reviewing the submitted papers.We sincerely hope that the ICCAER 2021 turned out to be a forum for excellent discussions that enabled new ideas to come about, promoting collaborative research. We are sure that the proceedings will serve as an important research source of references and knowledge, which will lead to not only scientific and engineering findings but also new products and technologies.Committee of ICCAER 2021list of Committee member, Organizing Committee Chair, Proceedings Chair, Technical Committee, Organizing Committee are available in the pdf.