This work aimed to present the optimum environment number methodology and propose the optimization of the National Sunflower Trials Network, by means of the environments exclusion that do not provide loss of the environmental variability already established. Grain and oil yield data of 16 genotypes evaluated at 16 environments of the National Sunflower Trials Network, obtained from trials conducted out-of-season in 2012 and 2013 were used. An analysis was proposed to establish the optimum environment number for genotypes evaluation, based on genotype performance in the various environmental combinations. The removal or maintenance of environments in the experimental network was dynamic, since different environmental combinations impacted the representativeness of the complete network in a different way. This analysis also provides a graphical view of the impact of the environment removal from the network. Once detected points below the established correlation, the researcher could infer about the network minimum environment number and, suggest through consistent information of several testing years, the environment exclusion.