This study focuses on flame hysteresis over a porous cylindrical burner. The hysteresis results from different operationprocedure of the experiment. Gradually increasing inflow velocity can transform the envelope flame into awake flame. The blow-off curve can be plotted by determining every critical inflow velocity that makes an envelopeflame become a wake flame at different fuel-ejection velocities. In contrast, decreasing the inflow velocitycan transform the wake or lift-off flame into an envelope one. The reattachment curve can be obtained by thesame method to explore the blow-off curve, but the intake process is reve.rse. However, these two curves are notcoincident, except the origin. The discrepancy between them is termed as hysteresis, and it results from the differencebetween the burning velocities associated with both curves. At the lowest fuel-ejection velocity, no hysteresisexists between both curves owing to nearly no burning velocity difference there. Then, raising thefuel-ejection velocity enhances hysteresis and the discrepancy between the two curves. However, as fuel-ejectionvelocity exceeds a critical value, the intensity of hysteresis almost keeps constant and causes the two curves to beparallel to each other. The study focuses on flame hysteresis over a porous cylindrical burner. The hysteresis results from different operationprocedure of the experiment. Gradually increasing inflow velocity can transform the envelope flame into awake flame. The blow-off curve can be plotted by determining every critical inflow velocity that makes an envelopeflame become a wake flame at different fuel-ejection velocities. In contrast, decreasing the inflow velocitycan transform the wake or lift-off flame into an envelope one. The reattachment curve can be obtained by thesame method to explore the blow-off curve But the intake process is reve.rse. However, these two curves are notcoincident, except the origin. The discrepancy between them is termed as hysteresis, and it results from the difference between the burning velocities associated with both curves. At the lowest fuel- ejection velocity, no hysteresisexists between both curves due to nearly no burning velocity difference there. Then, raising thefuel- ejection velocity enhances hysteresis and the discrepancy between the two curves. However, as fuel-ejectionvelocity exceeds a critical value, the intensity of hysteresis almost keeps constant and causes the two curves to be parallel to each other.