Assume that working procedure is only cutting tool′s breakdown,by using the method of probability and the theory of renew process,mathematic model that expected cost per unit time is objective function has been established,we take the interval of check and replacement of cutting tools as policy,the problem is to determine the o.

Current textbooks only discuss the condition under which the optimal quantity ordered should satisfies and do not give the concrete formulas for expected cost,which is an inconvenience for real practical uses.

From the viewpoint of risk control and management,a novel method for cost risk analysis based on hierarchy models is proposed according to the cost distribution characteristic of naval gun development,which is more objective than traditional methods.

For the sake of effective risk management, it firstly analyzes the risk content and finds out the difficulty, then it establishes a cost risk manage system and points out key problems.

In armament acquisition system, cost risk and the elements that had an impact on are interaction.