Background. The influence of fixation target and background on the sensory fusion status was studied. Methods. We examined the sensory fusion of eight normal subjects with a phase difference haploscope (PDH) under different background conditions: no background, a static background, and a dynamic background. Four sizes of a pair of similar pictures (faces) with four different kinds of suppression targets (nose, hat, mouth, and necktie) were used for test targets. During the 1-min fixation of these targets with the different backgrounds, we examined the location and the length of time the suppression targets disappeared. Results. The suppression targets of the small fixation target disappeared easily, compared with those of the large one. The duration of disappearance of suppression targets increased when the dynamic background was used. Conclusions. The small fixation target and the dynamic background exert a considerable influence on the state of sensory fusion.