This paper conducts a buckling analysis to find a relationship between the global load factor and reliability index in the case of a simply supported cylindrical lattice shell under dead and uniform snow load. First, the probabilistic properties of buckling load are studied to find the average and standard deviation. Second, the performance function is solved to obtain its reliability, leading the relationship between snow load factor and probability index considering 50 cm snow fall for 100-year reference period. Third, the relationship is converted to the relationship between the global load factor and reliability index. Finally, some applications and discussions are given for safety of the shells under severe snow load.