The structural parameters of combination tapered optical fiber surface enhanced Raman scattering (SERS) probes were designed and optimized. By building the excitation light attenuation coefficient model based on evanescent wave excitation on the nanoparticle’s surface of combination tapered optical fiber, and considering the total refraction theory of the excited light in the gradient core section and the mode-matching principle between the probe straight core section and the excitation fiber, the structure parameters design and optimization method of the combination tapered SERS probe were presented. With given fiber, nanoparticle structure, surrounding environment and input excitation power, an example of simulation design for the structural parameters of such optical fiber SERS probes were carried out by using the presented method.