Aiming at small size, compact structure, strong light-collecting ability, and low loss requirements of optical coherence tomography (OCT) probes used for human body detection, we design an all-fiber OCT probe, which is composed of a single-mode fiber and a multimode fiber (MMF) with spherical lens. By measuring the optical performance of these probes, we found that, when the length of the MMF of the composite probe is 372  μm and the diameter of the ball lens is 300  μm, it has the strongest focusing effect and a large reflected light signal receiving angle. Furthermore, the OCT probe studied was applied to a self-made spectral domain OCT system for validation. The results show that our probe can obtain a clear two-dimensional grayscale image of three layers of glass and fish scales, i.e., the probe manufacturing scheme can be used. Furthermore, it meets the needs of miniature OCT probes, which provides more effective options for measuring human blood vessels or other biological tissues.