 This paper proposes a new method to measure the force applied to a living cell using a glass needle. The method uses a multi-focus image fusion algorithm to accurately reconstruct the 3D spatial state of the needle and then calibrates it against a constructed calibration system. This allows the force to be measured at a high resolution of 0.002 μN and a low resolution of 5.3 μN. The proposed method can be used to measure the force applied to a living cell without requiring any additional physical sensors. This article was authored by Xiang Yu Guo, Yu Chao Zhang, Min Qian Chao, and others.