For better combustion performance of high burning rate composite modified double base（CMDB）propellant with ACP, a novel fast-burning energetic coordination compound of copper(Ⅱ) salt with one of triazole derivatives, ACP particles were coated with polyurethane adhesive. The thermal decomposition behaviors of ACP and coated ACP were studied by thermogravimetry (TG), and their effects on combustion performance of CMDB propellant in the pressure region of 11-20.5 MPa (high pressure range) and 3-9 MPa (low pressure range) were comparatively studied. Experimental results show that the thermal decomposition process of ACP or coated ACP includes four phases, and total loss of weight after decomposition are 90.70% and 76.22%, respectively. ACP and coated ACP are effective to enhance burning rates under low and high pressure and have about the same increments, and led to burning rate exponents enhancement under low pressure but reduction under high pressure. The propellants containing coated ACP show about 0.1 decrease in burning rate pressure exponent under high and low pressure in comparison with that of containing uncoated ACP with the same content in propellant. The experimental results indicate that the coating agent on the surface of ACP particles plays an important role in the thermal decomposition behaviors of ACP and affects combustion properties of propellants.