The invention provides a heating and temperature detecting method in tea processing, which applies electromagnetic heating and far infrared temperature detecting, wherein the electromagnetic heating comprises thermal insulation material, a heating coil, a magnetic conductive object and the like, and the far infrared temperature detecting comprises a far infrared temperature sensor and a temperature display device or a control device. The invention provides an electromagnetic roller steaming machine which consists of a steel cylinder, the heating coil, the thermal insulation material, a decorating plate, a guide pulley, the temperature sensor, transmission device, a stander, an electronic control cabinet and a guide vane strip; and the steel cylinder is heated in a way of electromagnetic heating, and the temperature of the steel cylinder is monitored in real time by the far infrared temperature sensor. The method has high energy conversion efficiency, little unavailable energy loss and no smoke and harmful gas emission, greatly reduces the air temperature of a workshop, and improves the work environment of the workshop; and furthermore, the method is sensitive and rapid in temperature response, can effectively reduce the fluctuation range of the temperature of the steel cylinder, is beneficial to accurately adjusting and controlling the electronic control cabinet, effectively improves the quality of enzyme-denatured leaves, and is even in deactivation of enzyme. Therefore, tea has obvious aroma and emerald green color.