Objective To investigate the value of contrast-enhanced ultrasonography in detection and diagnosis of small primary liver cancer. Methods SonoVue-enhanced ultrasonography were performed on 353 patients with 378 primary liver cancer, less than 3 cm in diameter. Enhancement patterns and enhancement phases of hepatic lesions on contrast-enhanced ultrasonography were analyzed and compared with the results of histopathology. Results In all hepatic tumors, 96.6% （365/378） lesions enhanced in the arterial phase. Among them, 317 (83.9%) tumors enhanced earlier than liver parenchyma and 48 (12.7%) tumors enhanced synchronously with liver parenchyma, and 342 (90.5%) tumors showed early wash-out in the portal and late phases. With regard to the enhancement pattern, 329 (87.0%) tumors presented whole-lesion enhancement, 35 (9.3%) to be mosaic enhancement and 14 (3.7%) to be rim-like enhancement. If taking the whole-lesion enhancement and mosaic enhancement in arterial phase as diagnotic standard for primary liver cancer on contrast-enhanced ultrasonography, the sensitivity was 92.9%(351/378), and if the earlier or synchronous enhancement of the tumor compared with liver parenchyma in arterial phase and the wash-out in portal phase were regarded as the stardand, the sensitivity was 87.3%(330/378). Conclusion Contrast-enhanced ultrasonography could display real-time enhancement patterns as well as the wash-out processes both in hepatic tumors and the liver parenchyma. It might be of clinical value in diagnosis of primary liver cancer based on the hemodynamics of hepatic tumors on contrast-enhanced ultrasonography.