Abstract: This article surveys the key technologies of solar sail spacecraft in the following four aspects,the global design, the orbit and altitude controls,the solar sail materials and their properties,and the folding and deployment of solar sails. For each aspect,the article summarizes the major contents and features according to the previous studies abroad and presents the recent advances in China,including the recent studies of the author's laboratory. Based on the successful achievements and detailed analysis on open problems,the article addresses some important issues,which will receive more attention when China develops solar sail spacecraft.