Thermal decomposition of NEPE propellant containing hexanitrohexaazaisowurtzitane (CL-20) at ambient pressure (0.1 MPa) and high pressure (2, 4, 6, 8 MPa) was researched with pressure differential scanning calormetry(PDSC). The results show that the temperature and heat of thermal decomposition are changed according to adding catalysts. The variation change with pressure. The PDSC characteristic values,which are the square roots of heat release rate and pressure on PDSC tests, can be correlate to burning rate of NEPE propellant containing CL-20 using a linear equation. k_r, correlation factor of burning rate with PDSC characteristic value was given. k_r can be used to analyze the influence of burning catalysts on burning rate of CL-20-NEPE propellant.