椭圆中与中点有关的问题一般可用“点差法”来解决,它可减少计算,达到简化运算的目的.本文旨在“点差法”的基础上,推导出此类问题更一般的结论和方法.由“点差法”我们可得如下:结论椭圆x2a2+by22=1内一点P(x0,y0),则以P(x0,y0)为中点的弦所在的直线方程为:x0xa2+yb02y=xa202+ The problems related to the middle point in the ellipse can generally be solved by the “point difference method”, which can reduce the calculation and achieve the purpose of simplifying the calculation.This paper aims to derive the more general conclusions and methods of such problems based on the “point spread method” . By the “spread method” we can get the following: Conclusion Ellipse x2a2 + by22 = 1 within a point P (x0, y0), then P (x0, y0) as the middle of the string where the line equation is: x0xa2 + yb02y = xa202 +