Diffuse optical tomography (DOT) is a novel functional imaging technique that has the vital clinical application. Aiming at the problems in DOT technology, we developed a three-wavelength continuous wave DOT system with high sensitivity and temporal resolution by adopting photo-multiple tube and photon counting detection, as well as lock-in technique. To assess the performance of the system, we conducted a series of cylindrical phantom experiments with optical properties that closely match those of human tissue, and obtained the reconstruction images by combining with our developed imaging scheme. The experimental results show that the position and size of the reconstructed targets are accurate, demonstrating the feasibility of the system. Additionally, the sensitivity, quantitativeness and spatial resolution of the imaging system were assessed by varying the target-to-background contrasting absorption contrast and target size. These preliminary results indicate that the system is scientifically capable of subcentimeter resolution imaging of low-contrast the lesion from the normal background.