A method for establishing a smooth geometric model based on data of a medical image includes: inputting or reading the data of the medical image; establishing a three-dimensional medical image voxel model based on the data of the medical image, smoothing the three-dimensional medical image voxel model, and establishing a three-dimensional voxel phantom tissue model based on the smoothed three-dimensional medical image voxel model; or establishing the three-dimensional voxel phantom tissue model based on the data of the medical image, and smoothing the three-dimensional voxel phantom tissue model. The method for establishing a smooth geometric model based on the data of the medical image smoothes the three-dimensional medical image voxel model or the three-dimensional voxel phantom tissue model to make it closer to the real situation of the human organ, thereby improving the reliability of the dose calculation to improve the quality of the treatment.