Abstract: Using the theory of free radical concentration fluctuation combined with the effect of optical tweezers, this paper studies the linewidth of femtosecond laser two-photon polymerization multiple-fast-scanning processing theoretically. According to the relationship between the change of free radical concentration and time in the two-photon photopolymerization processing, considering the influence of the optical tweezers on the free radical distribution range, it obtains the formula of the linewidth of multiple-rapid-scanning processing. It also presents the relationship between linewidth and scanning speed, laser power, and interval time. The results can be regressed to the general formula of single-scanning and are in good agreement with the experimental results in the literature. The study provides a new idea for studying the femtosecond laser two-photon processing to obtain a smaller processing linewidth, and provides a theoretical basis for the femtosecond laser multiple-rapid-scanning processing.