Pressure ulcers are serious complications of tissue damage that can develop in patients with diminished pain sensation and diminished mobility. Pressure ulcers can result in irreversible tissue damage caused by ischemia resulting from external loading. There are many intrinsic and extrinsic contributors to the problem, including interface tissue pressure, shear, temperature, moisture, hygiene, nutrition, tissue tolerance, sensory and motor dysfunction, disease and infection, posture, and body support systems. The purposes of this study were to investigate the relationship between buttock interface pressure and seating position, wheelchair propulsion speed. Seated-interface pressure was measured using the Force Sensing Array pressure mapping system. Twenty subjects propelled wheelchair handrim on a motor-driven treadmill at different velocities (40, 60, 80 m/min) and seating position used recline ($100^{circ}$, $110^{circ}$, $120^{circ}$) with a wheelchair simulator. Interface pressure consists of average (mean of the pressure sensor values) and maximum pressure (highest individual sensor value). The results of this study were as follows; No significant correlation in maximum/average pressure was found between a static position and a 40 m/min wheelchair propulsion (p>.05). However, a significant increase in maximum/average pressure were identified between conditions of a static position and 60 m/min, and 80 m/min wheelchair propulsion (p<.05). No significant correlation in maximum pressure were found between a $90^{circ}$ recline (neutral position) and a $100^{circ}$, $110^{circ}$, or $120^{circ}$ recline of the wheelchair back (p>.05). No significant difference in average pressure was found between conditions of a $90^{circ}$ recline and both a $100^{circ}$ and $110^{circ}$ recline of wheelchair back. However, a significant reduction in average pressure was identified between conditions of a $90^{circ}$ and $120^{circ}$ recline of wheelchair back (p<.05). This study has shown some interesting results that reclining the seat by $120^{circ}$ reduced average interface pressure, including the reduction or prevention in edema. And interface pressure was greater during dynamic wheelchair propulsion compared with static seating. Therefore, the optimal seating position and seating system ought to provide postural control and pressure relief. We need an education on optimal seating position and a suitable propulsion speeds for wheelchair users.