Example test demonstrates that,in the process of finding the optimal solution by using dynamic programming forward recursion method at present,the mistake about the range of the value of the production quantity x at the k stage and the storage quantity v at the end of k stage related to "production and storage model" is emerged,afer studying the optimal model about "production and storage problem",according to the principle for the minimization of the sum of total production cost and total storage cost,the correct range of the value of x and v is derived.