Photosynthesis is the most important energy conversion process on earth. It is of extremely important significance to the survival and development of the entire biological world and human beings, as well as to maintaining the ecological balance of nature. Chloroplasts are organelles unique to plant cells and are the site of photosynthesis. Therefore, the normal development and functional maintenance of chloroplasts are necessary for plant growth and development; the formation of functional chloroplasts is a prerequisite for plant photosynthesis. This project focuses on the systematic work carried out on chloroplasts and chloroplast gene expression regulation. Main contributions: (1) A chloroplast protein interaction network of Arabidopsis thaliana was constructed through systems biology and bioinformatics, and this network was used to functionally annotate 160 unknown proteins. This provides a useful resource for studying the related functions of chloroplast proteins. (2) Plastid-encoded RNA polymerase (PEP) is the main RNA polymerase in chloroplasts. Six nuclear factors involved in regulating chloroplast gene expression were identified, of which four (AtECB1, pTAC14, pTAC7 and FLN2) regulate PEP polymerase activity through interactions with PEP polymerase subunits, and two (PDM1 and AtECB2) are responsible for chloroplast post-transcriptional processing. These works provide an in-depth analysis of the basic biological process of chloroplast gene expression regulation. (3) The development of chloroplasts is the prerequisite for photosynthesis. Two important factors regulating the development of chloroplast thylakoid lamellae, AtECB2 and GDC1, were identified. Among them, AtECB2 is necessary for early chloroplast development and regulates the formation of chloroplast sheet structure; while GDC1 is necessary for the formation of chloroplast grana stack, which affects the formation of grana thylakoids by affecting the formation of LHCII trimers. Mining the functions of these two genes will help in-depth research on chloroplast development. The project applied this time belongs to the field of biomedicine technology, and its disciplines are related disciplines such as plant physiology, biochemistry and genetics in botany.  The project lasted for more than 10 years and published 14 SCI papers, of which 8 representative works were cited 272 times, and he cited 234 times. Many research results are in an internationally advanced position. It has successively received funding from various funds such as the National Key Basic Research and Development Plan Subproject (2009CB118504), 973 Pre-Research (2003 CCA01100), National Natural Science Foundation of China (31100965, 31570232, 31470337, 31370271 and 31100180), and Shanghai City Natural Science Foundation of China (10ZR1421800). He has published 8 representative papers in mainstream journals in this discipline including Cell Research, Molecular Plant, Plant Journal and Plant Physiology, and has been cited 272 times so far. Members of the project team have served as members of the 12th-13th Discipline Review Team of the National Natural Science Foundation of China (2008-2011), member of the Photosynthesis and Metabolism Professional Committee of China Society of Plant Physiology (2009-2012), Vice Chairman of the Shanghai Society of Plant Physiology, Professional Member of the Botany Society of China, Member of the Board of Directors of the National Center for Plant Genetics (Shanghai), Member of the Shanghai Society of Genetics, Editorial Board Member of J INTEGR PLANT BIOL, etc. Won the honorary title of ldquo; Shanghai City Shuguang Scholar rdquo;, was selected into the 2015 National Ten Million Talent Project, and was awarded ldquo; Young and Middle-aged Expert with Outstanding Contributions rdquo; Honorary title and won the 2015 Shanghai City May Day Labor Medal.