Continuous casting process is used for the solidification of molten steel into semi-finished shapes. Due to lack of reliable sensors online, manual monitoring was often essential to cooling control, which was time consuming and inefficient. This paper proposes an approach to automatically monitor high-temperature casting strand based on radiation thermometry, with the help of CCD (charge coupled device) camera and digital image processing technology. The bicolorimetric temperature measurement method is introduced in detail, as well as the working principle of CCD. Programs developed by Visual C++ 6.0 complete the acquisition, processing, calculation and visualization of casting strand image data. Besides, some experiment of temperature test was carried out for bloom casting (section size of 260 mm×300 mm) in a domestic steel plant so as to verify the monitoring model. Consequently, the purpose for monitoring casting strand is achieved, which is beneficial to cooling control in the process of continuous casting.