Based on a study of the timeprocess of individual evacuees in highrise building fires, we found that the lowsecurity influencing factor will affect the possibility of successful evacuation severely. The traditional grey relational grade cannot reflect the effect of the grey relational coefficient fluctuation. Moreover, the single weight calculation with a subjective or objective weight will also directly affect the evaluation result of safe evacuation during highrise building fires. Based on these analyses, the grey Euclid relative grade was applied to indicate the effect of the grey relational coefficient fluctuation. The Spearman correlative rating coefficient was used to combine the subjective and objective weights to eliminate the deficiency of the single weight case. We discuss the possibility of applying the improved grey relational evaluation. Comparing the evaluation results, we found that the weight combination and grey Euclid relation applied in a safety evaluation model can improve evaluation result accuracy. The evaluation model thus corresponds to the characteristics of highrise building fires and the weight set substantially affects the evaluation result.