The invention discloses an old-person monitoring system based on intelligent homes, a home terminal and a cloud service platform. The old-person monitoring system comprises a home terminal, the cloud service platform which is in communication with the home terminal and a client terminal which is in communication with the cloud service platform; the home terminal comprises a first communication module, an electric device control module for allowing a user to remotely control or locally control all kinds of electric devices in home space and sending control parameters of the electric device control module to the cloud service platform through the first communication module, an old-person-behavior-state monitoring module for monitoring behavior states of old persons in the home space and sending the monitored behavior states of the old persons to the cloud service platform through the first communication module and an old-person-medicine-taking reminding module for reminding old persons taking medicine to take medicine on time according to the quantity and sending the medicine taking states of the old persons taking the medicine to the cloud service platform through the first communication module; the cloud service platform comprises a second communication module, a processing module and a third communication module.