Fluidization experiments on coal char and quartz sand with different sizes were performed to determine the minimum fluidization velocity (MFV) in a fluidized bed with an inner diameter of 50 mm. The typical method of determining the MFV of single bed materials based on the intersection point of the fixed bed and the fluidization state pressure drop lines may not be used in some experiments because the pressure drop line is not straight and flat in a fluidized bed state, and the MFV cannot be obtained under this condition. Therefore, a new method based on the first intersection of the fluidization and the defluidization pressure drop lines for the narrow-meshed particles was proposed to supplement the typical method, and the MFV can be determined under any conditions. The correlations were proposed to predict the MFV of coal char and quartz sand, and the MFV was expressed as a function of Archimedes number. The correlation for coal char can also predict the MFV for biomass by comparing the calculated results with other correlations.