Calligraphy robots integrate calligraphy creation and robotics technology, simulate human writing behavior and calligraphy creation by controlling mechanical arm, and reproduce the charm of art. As a typical application of robot motion planning, robot calligraphy has important and far-reaching significance for the inheritance and education of traditional calligraphy culture. According to the research phase of calligraphy robots, the development course of calligraphy robots is reviewed and analyzed. This paper first introduces the key techniques of stroke separation and extraction, summarizes the two classic stroke models of virtual brush, then elaborates on the core technologies involved in writing trajectory, and applies different writing trajectory planning to control writing path. On this basis, the current writing evaluation metrics are analyzed, and the evaluation model of calligraphy robots is discussed. Finally, the existing research progress and process are reviewed, the advantages and disadvantages between traditional calligraphy robots and intelligent calligraphy robots are compared. It is presented to integrate the traditional writing trajectory path and stroke model into the training module of intelligent calligraphy robots to make up for its shortcomings in the writing sequence of strokes. At the same time, the paper looks forward to the future research direction and development trend of calligraphy robots. It is pointed out that the future research of calligraphy robots can focus on deep neural network, deep neural evolution and deep reinforcement learning, etc.