In this study, a jitter estimation algorithm during the acquisition period of non-overlapping images was proposed based on a double-constraint function. The double-constraint function was derived by combining the parallax-observation images with the low-frequency jitter to evaluate the smoothness of the jitter curve during the acquisition period of non-overlapping images. The conjugate-gradient method was used to find the smoothest curve, and the corresponding solution was used as the optimum estimation of jitter during the acquisition period of non-overlapping images. The quantitative relation between the jitter during the acquisition period of non-overlapping images and that during the acquisition period of overlapping images was established. The experimental results using the Chinese XX-1 space camera show that the jitter detection results are only valid when the measured jitter frequencies are neither equal nor close to any integer multiple of the characteristic frequency. This in turn proves that in such cases, the proposed algorithm can effectively detect the jitter during the acquisition period of non-overlapping images.