Abstract: With the wide application of large-span dome steel grid in large-scale public buildings such as gymnasiums, its high-altitude scattered construction is faced with problems such as complex structural stress, high risk of system conversion, and significant environmental temperature effects. Taking a large-span dome project in Meizhou as an example, this study aims to solve the problem of mechanical performance control of large-span dome steel grid in the whole process of high-altitude scattered construction, focusing on quantifying the risk of stress mutation caused by system conversion, and exploring the influence of environmental temperature difference on the mechanical properties of formed structures. Midas / Civil finite element software is used to establish a refined model of steel grid. Based on the actual construction process, the whole process of high-altitude scattered assembly is simulated by stages, and the temperature response analysis is carried out simultaneously. The results show that the maximum stress of each working condition is −35.2 MPa, and the maximum deflection is -6.41 mm, which meets the requirements of the specification, indicating that the safety of the assembly process is controllable. For the system conversion, the method of disassembling and supporting from the inner ring to the outer ring is more reasonable. After the conversion, the stress increases by 137.5% and the deflection increases by 122.2%. Under the action of dead load and ±20°C temperature difference load, the grid stress reaches 192.5 MPa and the deformation reaches 15.4mm, indicating that the influence of temperature stress is significant.