This paper studied the influencing mechanism on combustion noise in DT-diesel engines for turbocharged conditions. By measuring parameters of influencing combustion noise between natural aspirated and turbocharged diesel engine in constant torque and increasing speed transient and steady conditions, the change law of combustion noise in diesel engines was clarified. The testing result was thoroughly analyzed from the point of the combustion chamber’s wall temperature, aerodynamic load and high-frequency oscillation of combustion pressure. The result showed that the combustion noise of DI-diesel with turbocharger is reduced, and the reduction under turbocharged condition in steady condition is more obvious than that in constant torque and increasing speed transient condition, the effect of turbocharged condition on combustion noise is better in intermediate speed and middle load.