In this paper, an economic decisions-making model based on mathematics in order to optimize the costs of investment in accordance with innovative technology of human resources recruitment introduced and in the next section, the economic impact of the Internet recruitment technologies has been examined.  In order to fulfill these demands classic economic order quantity model of have developed as cover unique cost of recruiting activities such as human resource management and coordination related to it. Therefore, using this method calculated the required minimum of recruitment level and consequently optimal investment in online recruitment technology has been resulted. The findings suggest that optimal investment costs near the minimum level of recruitment is rapidly increasing but the stunning developments in efficient technologies in recruitment system and lack of awareness of this minimum level of employment has caused total number of employees is more than the required minimum level. In this article, how to use this model in a research sample of online recruitment websites in Iran entitled “Iran recruitment” its potential as a tool for decision-making in the field of optimal investment for managers appeared.