What style is Ou Yangxun's regular script called?

Ou Yangxun's regular script is called "European Style".

European style is a regular script font created by Ou Yangxun, a great calligrapher in the Tang Dynasty. It is characterized by the combination of harmony, strong stippling and cohesive brushwork. It is steep and rigorous. Keep the side stable, compact and sparse.

Introduction to Ou Yangxun:

Ou Yangxun (557-64 1), a native of Linxiang, Tanzhou (now Changsha, Hunan), is one of the four masters of regular script (Ou Yangxun, Yan Zhenqing, Liu Gongquan and Zhao Mengfu). Dr. Taichang, the official of Sui Dynasty, was named Prince of Gengling in Tang Dynasty, also known as "Ouyang Gengling". Together with the other three contemporaries (Yu Shinan, Chu Suiliang, Xue Qi), they are called the four masters of the early Tang Dynasty. Because his son Ouyang Tong is also good at calligraphy, he is also called "Big Europe". Ou Yangxun is known as the first regular script in Tang Dynasty for his rigorous brushwork and precipitous brushwork. He and Yu Shinan were both famous for their calligraphy in the early Tang Dynasty, also known as "Ou Yu". Later generations saw danger in peace with their books, and Xi Zhi, the first one, was named "Ou Ti".