Tunable localized acoustic fields have potential applications in the development of novel acoustic devices such as new filters, sensors and acoustic manipulation micro-devices. In this paper, tunable localized acoustic fields on a defect phononic crystal plate (PCP) have been numerically investigated. The results showed localized acoustic fields on a defect PCP can be tuned by changing the resonance frequency. It is attributed to the inconsistency of the resonate frequency for the defect hole and the periodic holes in the defect PCP, which induce various coupled fields on the surface of the defect PCP. This designed defect PCP can be used as acoustic holder for the investigation of the interaction between the acoustic field and microparticles.