To solve the fixed direction problemin traditional medical imaging technologies and satisfy the clinical medicine requirement of observing the organ in term of the whole or sections from different viewpoints,a three dimensional visualization method of the cardiac MRI data to display the whole heart volume and the arbitrary-cut sections is proposed.Using VC6.0 and VTK,the ray casting method is adopted to realize the threedimensional visualization of total and partial cardiac MRI data and the virtual sections from arbitrary viewpoint.Simple interactive operations such as scaling,translation and rotation can be realized in real time.The experimental results show that the presented method can assist doctors to observe the organ tissue and sections from different viewpoints,which is valuable in disease prevention,medical diagnosis,surgical planning and postoperative evaluation.