To study propeller fluctuating pressure characteristic of highspeed twin-propeller ship in cavitation condition, a propeller open water test is conducted in deep water towing tank, while propeller after hull performance, fluctuating pressure measurement, and cavitation observation tests are conducted in a large circulating water channel with a complete ship model. The test results show that the maximum amplitude of fluctuating pressure increases with propeller speed, and unstable sheet cavitation leads to the increase in higher order components of fluctuating pressure. With the development of cavitation, the location of the maximum amplitude of fluctuating pressure moves to the inside of the model until distribution of fluctuating pressure keeps constant when the propeller reaches a certain speed. A computational fluid dynamics (CFD) numerical method to evaluate fluctuating pressure and cavitation of propeller is established using the shear stress transport (SST) k-ω model and the VOF method. The comparison of numerical and test results illustrates that the numerical results of fluctuating pressure have a good agreement with test results in non-cavitation and high rotation speed conditions, but the numerical values calculated are larger due to imprecise simulation of unstable sheet cavitation. There exists a large error in the numerical results of fluctuating pressure on the inside of the model which results from the attenuation of the value calculated and the phase difference of the two propellers in the test.