Diversity of nematode fauna in relation to their occurrence in high temperature cotton growing areas of Sindh by using Euclidean distance has been estimated. The fauna obtained in June2017 and June 2018 surveys of cotton fields of five Districts Sanghar, Mirpurkhas, Umerkot, Mitiari and Tando Allah Yar of Sindh where temperature in May to July raised up to 40ºC -50ºC.The data was subjected to construct the dendrogram for interpretation on the basis of their prevalence. In order to estimate nematode species diversity, richness and evenness, the data has been submitted for calculating the diversity parameters such as Dominance (D), Simpson’s diversity index (1-D), Shannon diversity index (H’), Evenness (e), Brillouin Diversity Index (HB), Menhinik Diversity , Margalef's richness index, Equitability (J) and Fisher's alpha. All estimated parameters of diversity has interrelation among all nematode genera in particular but no correlation have been found establish between genera with reference to temperature fluctuation during studied years.