The art of calligraphy is embodied in practical words. Whether it has charm and beauty is the most basic principle for appreciating calligraphy. The beauty of calligraphy can only be expressed in two aspects: "real" and "virtual", that is, "form" and "temperament". The "real" aspect is tangible and visible. It refers to the external form. Appreciation is mainly based on lines and frame structure, and includes the use of pen, structure, composition, etc. The use of pen can be divided into slow and urgent, ups and downs, and twists and turns; the front of the pen can be divided into positive and side, hidden and exposed. The shape of strokes can be either square or round, and it also pays attention to the strength and posture of the strokes. The structure includes legal principles such as odd and straight, sparse and dense, and violation of harmony. The composition includes guest and host, virtual and real, avoidance, coherence of Qi and pulses, and the form of rows and columns. There are differences between the three and they complement each other. The aspect of "virtual" (temperament) is intangible, which refers to the inner spirit. The author's personality characteristics and artistic style must be recognized from the treatment of lines and structure, including expression, charm, artistic conception, etc. The two aspects of "real" and "virtual" are interdependent and use each other to express the aesthetic value of calligraphy works.