The mathematical expression of Gann line has two basic elements, price and time. Gann combines price and time perfectly through Gann Circle, Gann Spiral Square, Gann Hexagon and Gann "Wheel in Wheel". In Gann's theory, seven is a very important number. Gann often uses "seven" or multiples of "seven" when dividing the market cycle. Gann believes that "Seven" combines the concepts of nature, astronomy and religion.

Gann line is an important concept of Gann theory and investment method. Gann establishes time on the X axis and price on the Y axis, and the symbol of Gann line is represented by "TXP". The basic ratio of Gann line is 1: 1, that is, a unit time corresponds to a price unit, and the Gann line at this time is 45 degrees. Through the analysis of the market, Gann is divided into three or eight shares, such as 1/3, 1/8 and so on. These Gann lines constitute the support position and resistance position of the market callback or rise.