三体问题是天体力学中的基本力学模型。

它是指三个质量、初始位置和初始速度都是任意的可视为质点的天体，在相互之间万有引力的作用下的运动规律问题。

现在已知，三体问题不能精确求解，即无法预测所有三体问题的数学情景，只有几种特殊情况已研究。

In physics and classical mechanics, the three-body problem is the problem of taking an initial set of data that specifies the positions, masses and velocities of three bodies for some particular point in time and then determining the motions of the three bodies, in accordance with the laws of classical mechanics (Newton's laws of motion and of universal gravitation). The three-body problem is a special case of the n-body problem.