The control and data processing system for four-channel microwave radiometers controlled by a single chip microprocessor is discussed. The system contains the interface circuit, data acquisition circuit, sequence control circuit and control and data processing module. The real-time multi-task operating system for the single chip microprocessor was designed. The software design contains task management, task communication, clock, input-output and interrupt management. The advanced digital modulation-demodulation technology for data managing methods was adopted. The system has capabilities of real-time control, data collection, real-time display and communication, etc., and has simple structure, small size, low cost and high reliability, thus has broad prospects in application.