Provided is a cloud system for menstrual cycle prediction, including a cloud server device, having an identity recognition unit, a memory unit, a transmitting module, a receiving module, a cloud database and an arithmetic processing unit a test strip detection device, measuring a physiological hormone value of a plurality of test solutions from a user and a portable electronic device, having a transmitting unit, a receiving unit, a display unit and a storing unit. The physiological hormone values of the plurality of test solutions that are measured by the test strip detection device are stored in the storing unit of the portable electronic device and are transmitted to the memory unit of the cloud server device, and the predicting of physiological menstrual cycle data of the user is performed by the arithmetic processing unit of the cloud server device.
