There exist misdiagnosis and missed diagnosis with routine ultrasound imaging of thyroid nodules in present clinic. A novel method employing a series of long-focal-zone focused transducers with different frequencies for photoacoustic imaging (PAI) is presented. Some blood clots in different sizes are embedded in tissue-mimicking phantom to form a phantom containing specific pathological lesions. Transducers with different frequencies are used to image this phantom photoacoustically. Furthermore, blood is injected into normal human thyroid tissue, forming two blood stasis areas. Three-dimensional imaging is available by performing two-dimensional scanning through the tissue. We demonstrate that transducers with different frequencies have different sensitivities in detecting lesions of different sizes. The broadband transducer with a center frequency of 5 MHz has a better sensitivity in detecting lesions ranging from a few hundred microns to several millimeters. Therefore, a high resolution and excellent contrast three-dimensional image of the thyroid tissue with two blood stasis areas is obtained. This technique integrated with ultrasound imaging has the potential to increase the diagnostic accuracy in clinical thyroid nodule diagnosis.