This paper studies a joint ordering, pricing and preservation investment decision problem for perishable items. It is assumed that the demand rate is dependent on price and inventory level simultaneously, shortages are not allowed and the restriction of zero ending-inventory is relaxed. And meanwhile considering that the deterioration rate can be controlled by employing a certain preservation technology and the retailer has limited shelf space or storage space. The inventory model of the joint ordering, pricing and preservation investment decision for deteriorating items with inventory-level-dependent demand is proposed with the goal of maximizing the retailer's average profit. First, it is proved that the optimal policy not only exits but also unique, and we also provide the conditions for retailer to build up inventory. Then, an iterative algorithm is designed to find the optimal solution according to the relevant properties of the model. Finally, the numerical example is given to illustrate the feasibility and practicability of the model and algorithm, and the sensitivity analysis of relevant parameters is carried out and some managerial insights are derived.