Abstract: In order to reveal the operation feature of 5 MW heating reactor, a series ofexperimental study have been done, including the disturbance of normal operationcondition, load following feature and transient feature during reactivity insertion.The experimental results indicate: when the load change is ±40% and reactivityinsertion is 2 mk, the 5 MW reactor can go to another stable condition safely andsmoothly without any external interference.