The invention discloses a three-dimensional volume data visualization parallel rendering method based on OpenCL. The method comprises the steps of three-dimensional volume data reading, coordinate normalization, viewpoint coordinate transformation, ray and volume data intersection point calculation, self-adaptive sampling, smooth interpolation and gradient calculation, and three-dimensional visualrendering according to color values of sampling points and an opacity accumulation result. According to the invention, the attenuation function is used as the sampling density function of the adaptive sampling method to perform non-uniform sampling, so that computing resources can be efficiently utilized, and the rendering effect is improved; and smooth interpolation and gradient calculation arecarried out on sampling points by adopting a cubic B-spline function, so that a higher degree of freedom is provided on the premise of ensuring relatively low calculation complexity, and a smoother rendering result can be obtained.