According to the fluctuation range of opening price and closing price, K-line can be divided into extreme yin, extreme yang, small yin and small yang, middle yin and middle yang, and big yin and big yang. The fluctuation range of extreme yin line and extreme yang line is about 0.5%; The fluctuation range of xiaoyin line and xiaoyang line is generally 0.6-1.5%; The fluctuation range of Yinzhong Line and Zhongyang Line is generally1.6-3.5%; The fluctuation range of Yin Da Line and Dayang Line is above 3.6%.