摘要:相对论是青少年最感神奇，也觉得最为难懂的科学理论。然而，由于相对论的时空观念与经典物理学以及人们生活中的直观感受有很大不同，老师和同学们往往觉得理解上非常困难。对于同学提出的五花八门的问题，老师感到难以招架。为了能够对大学和中学的相对论教学有所帮助，本文在纯粹的数学几何逻辑中，假设参考系中光运动的轨迹线长度为光运动的时间(即：光速 = 1 = 1光年/年 = c米/秒)，解出坐标变换、速度变换，得到《狭义相对论》的几何原理，帮助老师和同学们真正理解《狭义相对论》的洛伦茨变换、动钟变慢、质能方程，并促进相对论的研究和发展。

Abstract:Relativity is the most magical and difficult scientific theory for teenagers. However, because the space-time concept of relativity is very different from classical physics and people's intuitive feelings in life, teachers and students often find it very difficult to understand. Teachers find it difficult to parry the various questions raised by students. In order to be helpful to the teaching of relativity in universities and middle schools, In the pure mathematical geometric logic, this paper assumes that the length of the track line of light motion in the reference system is the time of light motion (Namely: light speed = 1 = 1 Lightyear/year = c m/s), solves the coordinate transformation and speed transformation, and obtains the geometric principle of special relativity, Help teachers and students really understand Lorentz transformation, slowing down of moving clock, mass energy equation in special relativity, and promote the research and development of relativity.