At high inlet pressure extent (P-avg = 20 MPa) in water hydraulic fields, the relationship between inlet pressure fluctuations and unsteady cavitation process condition inside a water hydraulic poppet valve has been numerically analyzed using a two-phase mixture model via computational fluid dynamics (CFD) software ANSYS Fluent 14.5. The effects of different inlet pressure fluctuations and a groove at valve port on unsteady cavitation process and flow field are investigated. The results reveal that under sine-wave-type inlet pressure fluctuations condition, unsteady cavitation process and flow field physical parameters show periodic changing characteristics; cavitation content inside valve port is more related to the value of amplitude A and frequency f. In a certain extent, increasing or decreasing frequency f can suppress the occurrence or enhancement of cavitation. The existence of a groove at valve port can reduce the intensity of cavitation under inlet pressure fluctuations condition. (C) 2016 Elsevier Ltd. All rights reserved.