K-line chart, also known as Yin-Yang candle, was originally a tool used by Japanese rice merchants to express the rise and fall of rice prices. Later, it was introduced into the stock market and gradually became popular in Southeast Asia. K-line chart is welcomed by investors because of its intuitive and three-dimensional characteristics. Practice has proved that careful study of the K-line chart can accurately predict the market outlook and clearly judge the strength comparison between long and short sides, thus providing important reference for investment decision-making.