In this work TATB has been used to desensitize the sensitivity of CL-20. The influences of TATB particle size and content and of CL-20 particle size on the sensitivity of CL-20 has been investigated. Experimental results show that the desensitizing effect is better with CL-20 particles being larger and TATB particles smaller. It has been discovered that the mechanism that TATB desensitizes CL-20 is that a layer of TATB is formed on the surface of CL-20 particle.