Introduction: There was always suspicion regarding concept and frameworks of digital libraries concepts such as electronic library, virtual library, without wall library, hybrid library and digital library have applied often together, or for each other for conveying library concept. Studies have shown that so far there is no standard and universal accepted definition for digital libraries, however Digital Library Federation (DLF) has a definition that is most accepted and cited definition. This study aimed to determine the most important parameters for designing and evaluation of digital libraries and provide a relatively criteria framework had been given.

Methods: In this descriptive research, studying texts and reviewing resources about digital libraries and their designing and evaluation we recognized a lot of elements in designing digital libraries. Then we surveyed six successful world digital libraries and analyzed information to determine basic parameters in designing of digital libraries. 

Results: The 14 main parameters in designing of digital libraries are as followed: full text recourses, special users, permanent access, format, retrieval and search, acquisition,infrastructures and equipments development, expert staff, organization, cooperating capability with other libraries, services, print resources, standards and standardization, and copy right observance. Every Parameter has different subsections, involving different areas.

Conclusion: We did not find any study about investigation of parameters related to designing and evaluation of digital libraries. Our finding may be used as designing and evaluating criteria for digital libraries and improvement of actual process in these libraries in the future.