The general environmental factors that influence fixation distribution as part of pedestrian visual behaviour under natural conditions are unclear. Relative luminance and saliency are considered the parameters for predicting image-based fixation; however, they are not confirmed by evidence from the natural walking scenario. Field experiments using mobile eye-tracking glasses device were conducted on 16 participants in four commercial streets during day and night. Fixation data along with processed images extracted from eye-tracking glass video were analysed to investigate if relative luminance or saliency correlates with fixation distribution while walking. The results show that fixations within a 10° viewing angle were distributed in bright and more salient areas in the field of vision. Statistical analyses found a stronger positive correlation in saliency than in relative luminance and at night-time rather than under daylight. The correlation found between relative luminance/saliency and fixation distribution suggests that relative luminance/saliency may attract the visual attention of pedestrians. It will be beneficial for practical applications via a better visual environment, including lighting and guiding facilities for pedestrians, especially at night.