This article aims at studying and analyzing the methodology of research in four approaches in dialectology, namely dialect geography, social dialectology, perceptive dialectology, and corpus-based dialectology as traditional and modern approaches in the field. After a brief review of the principles of historical –comparative linguistics as the origin of dialectology as a field in linguistics, the literature, the goals, methods of data gathering, analysis, and presenting the results will be discussed. A descriptive and comparative method is used for studying each approach, and presenting a methodological model.  Dialectology which has been introduced partly as a response to some principal claims of historical-comparative linguistics, have undergone numerous changes regarding the methodology over the past century, mainly as a result of the developments in the technology of gathering, recording and analyzing the data, and also the interdisciplinary trends. While focus of traditional dialectology was on gathering and describing mainly the phonological and lexical features of non-mobile old rural male informants, social and perceptual dialectology focus on analyzing the effects of social factors and language attitudes on linguistic features and the perception of linguistic borders. Corpus-based dialectology is based on computational and statistical analyses. So, modern approaches focus on dialects of different communities in rural and urban areas, language attitudes, different linguistics features including grammatical and morpho-syntactic, corpus-based and cognitive analysis, quantitative and qualitative analysis using computer and statistics in gathering and analyzing the data.