Abstract: Noise disturbance is a key problem which should be taken into account in accurate optical flow estimation, since image data may be blurred in capture and transmission process. To resolve this problem, firstly, the two hypotheses of traditional optical flow method were discussed, through which the limitations of the luminance constant hypothesis were unveiled; and then, according to the noise constraint, the basic optical flow equation was corrected based on the MUKAWA’s results; after that, the global smoothness constraint of optical flow field was introduced to regularize the problem of optical flow estimation, based on the new basic optical flow equation; finally, the arithmetic expressions of determining optical flow field were deduced from the new basic optical flow equation and the global smoothness constraint using the variational approach. The CAVIAR video data were used to test our method. Firstly, the test data were added in the Gaussian noise with different levels; and then, the optical flow fields of these blurred data were determined using traditional methods and our method, respectively; finally, the experiment results with different methods were analyzed and compared. Both of the test results and comparative results showed that our method outperforms the others in the presence of noise.