The modern way of life is increasingly encouraging tourists to meet their needs for staying in pristine and clean natural environments. Therefore, wealth and preservation of natural resources are a key prerequisite for tourism development in the area of national parks. By increasing the number of visitors that affect the environment, there is a need for adequate exploitation of natural resources for the purpose of their preservation. In order to ensure further satisfaction of visitors' tourist needs, while preserving resources from over-exploitation, it is necessary to develop sustainable tourism that controls the impact of tourism development on the natural environment. The concept of sustainable development, especially in terms of national parks, is often equated with ecological sustainability, but sustainable development of tourism is not possible without the acceptance of socio-cultural characteristics and economic and technological sustainability. Economic sustainability of national parks implies management's ability to ensure the ecological, socio-cultural and economic long-term sustainability of national parks through the promotion of tourism products. By analyzing the financial plans and on the basis of the results of the conducted survey, it was determined the importance of the financing of projects from EU funds to the economic sustainability of national parks. Ecological sustainability, which is crucial for these areas, is expressed through the overall capacity of long-term renewal in its basic ecological characteristics. It is important to take into account the space capacity as the upper limit of tourist traffic in national parks. Along with the trend of growing globalization of tourist offer, one of the strategic goals of national parks is to provide quality visits with a high degree of organization and minimal harmful impact on ecosystems through the implementation of the measure of the development of the visit system. Social sustainability depends on the level of development of the local environment, so the traditionally local population is less open to social change. Local community cooperation and institutions managing protected areas of nature is one of the starting pillars of the development of a protected area. Maximizing the positive effects that the local population has on tourism encourages local community activism with the aim of enhancing the protected area. In order to ensure the sustainable development of national parks, it is necessary to achieve a compromise in changing all principles of sustainable development.14 The purpose of the dissertation is to determine the current state of affairs through secondary sources related to arrivals, departures and number of beds, but also through a primary research based on contributing to tourism in protected areas by examining the attitudes of employees and the local population. Employees are mainly residents of the area, and their responses to the possibility of staying in the area are not significantly different. The biggest differences between the views of the local population are the Continental Croatia which includes the "National Park Plitvice Lakes", "National Park Risnjak" and "National Park Northern Velebit", and Adriatic Croatia: National Park Brijuni, National Park Kornati, National Park Krka "," National Park Mljet "," Paklenica National Park ". Carrying capacity and the viability of the destination through the basic indicators of tourism development and in relation to the local population it is clearly seen the degree of tourist development of the destination as well as the interest of the local population for the further development of the municipalities and cities especially in the rural area. Croatian national parks, as well as all tourist destinations in Croatia, are facing the challenge of monitoring the dynamic trends of tourism supply and demand and the application of new management models. In spite of good publicity and the increase in revenue, parks are still facing the task of increasing the awareness and recognition of demand from a large number of new markets, ie the active use of new marketing models. Based on the conducted analysis, the primary research has confirmed the hypothesis of the research, a model and strategy for sustainable tourism development in National Parks has been proposed, especially in rural areas that are ecologically preserved with respect to the demographic picture of the population and the educated structure we can apply new models of tourism development.