For the optimal selecting problem of risk response actions in software project risk planning stage, an interval
model is proposed, which selects the satisfactory combination of risk response actions according to the minimum of risk
response cost and risk level, combined with decisionmaker’s risk preference, from the whole project perspective. Due to gain
the exact value of risk probability and risk loss with very difficulty, the model denotes the parameters by interval numbers.
Then, an iterative algorithm based on the definition of interval distance and the method of interval numbers ranking is given
to solve the model. A case analysis shows the effectiveness and the maneuverability of the model and the algorithm.