通过模拟单光线在双层介质球各界面上的反射和折射，分析了单光线对介质球施加的作用力，进而计算了整个高斯型激光束对小球施加的作用力。计算双层球的内层折射率分别为1.0和1.9时的捕获力，分析小球内层的半径和折射率对光镊捕获力的影响。计算结果表明，不同内径和折射率对捕获力的影响显著。当内层折射率小于外层折射率时，光镊捕获的稳定性得到提高，但是捕获的空间范围被压缩；而当内层折射率大于外层折射率时，光镊的捕获性能降低。双层球捕获力的分析结论为该类小球用做光手柄提供了可靠的理论依据。

By simulating the reflection and refraction of single-ray at each interface of double-layer dielectric sphere, the force exerting on the dielectric sphere by a single ray is analyzed, and the force exerting on the sphere by the total Gaussian laser beam is calculated. The axial force is calculated when the refractive index of inner layer of double-layer sphere is 1.0 and 1.9, respectively, and then the influence of the refractive index of inner layer on optical tweezers trapping force is analyzed. As shown by the calculation results, the influence of different refractive indices and radii of inner layer on trapping force is notable. As the refractive index of inner layer is smaller than that of the outer layer, the stability of optical trapping is improved, but the spatial scale of trapping is reduced. And the performance of optical trapping is reduced as the refractive index of inner layer is larger than that of the outer layer. Analysis conclusion of the force trapping double-layer sphere provides reliable theoretical basis for this kind of sphere used as an optical handle.