Abstract: Zero power reactor experiment is an indispensable stage for the design of new reactor. In order to scientifically assess the similarity of physical characteristics between systems, three indexes were introduced to evaluate the physical similarity between systems based on the sensitivity and uncertainty analysis techniques. Based on the results of MONK sensitivity calculation under continuous energy, a similarity analysis program was developed. And then the results of the program were compared with those of TSUNAMI and showed good agreement. The two main similarity indexes C_k and E were analyzed when greater than 0.95, greater than 0.9 and greater than 0.8. The results show that the similarity indexes between systems need to be greater than 0.9 to ensure adequate verification potency or similarity. Taking the Pb-Bi fast reactor as the target reactor type, the zero power reactor physical design was carried out using the similarity analysis method.