Abstract: In the transportation of fresh fuel assemblies, one of the most important problems that the review department cares about is criticality safety. In this article, the criticality safety analysis on the fuel assembly transportation of China Advanced Research Reactor is taken by MCNP code. The calculation is conservative by ensuring the subcritical limit, model parameters and accidental conditions. As a result, the criticality safety index of the transport package can be determined as 0. The collusion of this article can provide reference to the researching and manufacture of the transport package for CARR fresh fuel assembly.