Abstract: Effects of external force on the gelatinization characteristics of starches from various sources were studied at different rotate speeds by a rapid viscosity analyzer. The gelatinization behavior under various external force and the mechanical stability of starch paste were assessed for the quality control of starchy foods. Viscosity curve and mechanical stability depended on sources of starch. Among the starches, wheat starch had the lowest gelatinization temperature. Potato starch paste showed the highest viscosity and temperature stability. Potato and lotus-seed starches exhibited high viscosity and cold paste stability. Lotus-seed starch showed the lowest hot paste stability. Corn starch had easy retrogradation. External force could affect the viscosity curves of the starches .Stronger external force could depress intensity, viscosity and gelatinization temperature of the starch paste, and improve stability of both hot paste and cold paste. Mechanical stability of the starch paste was related to the intensity of starch granule. The starch granule with high intensity owned high mechanical stability.