China Fusion Engineering Test Reactor (CFETR) is aimed to meet the technical gaps between International Thermonuclear Experimental Reactor (ITER) and future fusion DEMO reactors, tritium self-sufficiency must be guaranteed for the operation of fusion reactors. Helium Cooled Ceramic Breeder (HCCB) blanket is one of the promising candidate blanket schemes for CFETR. Tritium generated in Li4SiO4 pebble bed is carried out by purge gas, it is crucial to study the tritium behavior in the blanket from the tritium fuel cycle point of view. In this paper, the effective diffusivity of tritium in purge gas is conducted based on Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) coupled simulation considering the influence of the pebble bed structure. The flow characters analysis of purge gas is carried out by CFD simulation as well, which includes velocity field distribution, pressure field distribution and pressure drop. Based on the macro parameters conducted above, the tritium transport process in blanket including tritium permeation into coolant, tritium inventory in blanket and tritium carried out by purge gas is simulated based on a 2D model set up in COMSOL Multiphysics, the results can be the reference for the design of Tritium Extraction System (TES) and Coolant Purification System (CPS).