Is the hard pen calligraphy paper written horizontally or vertically?

Both will do. According to calligraphy net's information, the format of hard-pen calligraphy works is mainly selected according to personal habits and overall beauty, which can be written horizontally or vertically. Calligraphy is an artistic expression of the unique beauty of words in China and neighboring countries and regions deeply influenced by China culture. Include China's calligraphy and Mongolian writing.