Abstract: Cryptochromes are blue light receptors which share the similar function with the phytochromes in regulation of the growth and development in plants. After 90’s, especially in the recent years, profound studies have been carried around the cryptochromes. Cryptochromes were found not only in plants, but also in aminals. It has been known that cryptochromes are involved in de-etiolation in seed germination, photoperiodic-inductive flowering, regulation of circadian rhythm, etc. In the article, we introduced the characteristics of cryptochromes and the genes, including cryptochromes structure, the presence in plant kingdom, the localization in cells, and the expression regulated by light. In addition, the function of cryptochrome in plant photomorphogenesis and in controlling of the circadian clock in plants and animas was summarized. Through analysis of the relationships between cryptochromes and the interacted proteins, we clarified primarily the roles of how cryptochromes mediate the plant growth and development via interacting with proteins in the signal pathway. It was suggested that studing the cryptochromes and their signal transduction profoundly to disclose the nature of plant photomorphogenesis will be of great importance both to biologic theory as well as application.