Provided is a method of building a cloud-based medical image database for protecting patient information and reading medical image therefrom, the method including: acquiring a medical image of a patient by using a medical apparatus; separating medical information data and patient information data from the medical image; encrypting the patient information data by using a block chain technique; separately transmitting the encrypted patient information data and the medical information data to the cloud-based medical image database, and storing the same in the cloud-based medical image database; decrypting the encrypted patient information data stored in the cloud-based medical image database by using a block chain technique; and performing diagnosis and consulting by reading the medical information data and the patient information data of the medical image according to a big data processing algorithm. Therefore, the method may protect patient's personal information and determine the cause and progress of a disease.