"海島算經" is an ancient Chinese mathematical treatise written by Liu Hui in the III-IV century AD. e. The book consists of 246 problems that relate to arithmetic, geometry and various practical applications of mathematics at that time. "海島算經" presents a variety of calculation methods, including operations with fractions, triangles, and even calculating the areas and volumes of various geometric figures. This book is an important source for the study of the development of Chinese mathematics and is of great importance for the history of science.