In this paper, we propose a thermoacoustic (TA)and photoacoustic (PA)dualmodal imaging system for early breast tumor detection. In this system, pulsed microwave and pulsed laser are respectively used as excitation source of TA and PA imaging. The generated TA and PA signals are received by the same ultrasonic detector and the same data acquisition device, and the image is reconstructed by the same imaging algorithm. The system can obtain multiple complementary diagnostic parameters simultaneously to improve the accuracy of early detection of breast tumor.