Pulse duration is considered as one of the most important characteristics of high-power femtosecond lasers. However, pulses output from the laser system are susceptible to ambient changes and manifest the instability of pulse durations in an open environment. In this paper, incorporating the algorithmic framework of the improved stochastic hill-climbing search and incremental proportional-integral controller, temperature-induced fluctuations of pulse duration can be effectively compensated by an automatic feedback control in an all-fiber chirped-pulse amplification system. In the experiment, sub-hundred femtosecond fluctuation of pulse duration is introduced to verify the performance robustness of the proposed pulse-duration feedback control (PDFC). The stability of pulse duration is obviously higher than the case without the feedback control, and the peak-to-peak fluctuation of pulse duration is reduced to 6.5%. Furthermore, the robust switching between different pulse durations proves the versatility of the PDFC. We expect that the proposed feedback control method could provide a novel insight into high-power femtosecond lasers widely applied in fundamental researches and industrial fields.