Abstract: Transfer function is an important tool for direct volume rendering of 3D visualization of heart. However, the complexity of heart structure makes the design of transfer function a difficult task. In this paper, we introduce visibility histogram based transfer function to display the cardiac dual source CT data. We first preprocess the cardiac dual source CT volume data and afterwards explore the transfer function based on visibility histogram. Furthermore, we propose the automatic method to design the transfer function. With these methods, users can highlight the region of interested and even observe more details of cardiac chamber. Finally, we accelerate the calculation and 3D rendering using the technology of CUDA, thus leading to the real-time dynamic display of three-dimensional volume data. The experiments show that the proposed method can effectively remove the ribs, pulmonary veins in cardiac dual source CT data, enhance the myocardial tissue, blood and some internal structures such as the aortic valve, which is of great importance for cardiologists in clinical diagnosis.