Thermal sensation of users in outdoor spaces is an important aspect for an effective open space design. Vegetation is a serious component of the urban environment to alleviate the negative impacts of Urban Heat Island. In a hot city, the suitable plantation of trees is an essential parameter that can reduce heat stress. The objective of this study is to examine how the arrangement of trees and terrestrial materials can affect the outdoor microclimate and thermal comfort in business parks. This research focuses on optimizing the arrangement of trees with specific spatial location, in order to create green business park`s landscapes. Moreover, substituting high emission thermal terrestrial materials by low emission ones plays a key role in modifying the outdoor microclimate. In order to reach the goal, the current situation of an Egyptian business park called “Silicon Waha” was simulated, as a case study, using ENVI_MET software to investigate the levels of human thermal comfort. Afterwards, nine scenarios considering various tree layouts with specific pavement improvements were conducted. The results obtained were then compared with the actual design to determine the best alternatives for ameliorating the outdoor microclimate and enhancing human thermal comfort. Therefore, the paper develops a methodology of a relation between selecting trees location and the environmental parameters in Business Parks located in hot-arid climate. Eventually, the findings of this research provide the stakeholders with better guidelines for improving thermal comfort in outdoor workspaces and developing sustainable cities.