Edge computing is a novel computing paradigm which extends cloud computing storage and computation resources at the edge of network and closer to the end-users in order to tackle the problem of communication latency in latency-sensitive applications. For the last decades, there have been many research efforts dedicated to this field. However, there are still many operational challenges. The dramatic growth in researches, large volume of published studies, and the attention of researchers in this field in recent years have made it necessary to conduct a Systematic Mapping Study in this field. we need a comprehensive guide to enable researchers to do more effective searches on each scope of edge computing. An important part of the methodology is to use the appropriate search method using a three-tier strategy. In this method, we defined some quality criteria to extract search spaces and studies with the highest quality for reading and analysis. In a separate phase, we evaluated the extraction process of related studies in terms of accuracy. using this comprehensive methodology, we select the number of 112 search spaces out of all 805 ones and by search in these search spaces we select 1440 high-quality studies out of 8725. In our Systematic Mapping Study, 8 research questions have been designed to achieve goals such as identifying the main topics, architectures, techniques, and so on in the field of edge computing. We aim this paper can serve as a guideline for researchers interested in this field.