Aiming at the questions of raceway section twodimension temperature distribution from twodimensional image accumulated by threedimensional radiation space and threedimensional temperature reconstruction error caused by limited charge coupled device (CCD) sensors for a sudden spread combustion chamber, the twodimension rectangle interpolation virtual CCD sensor installation algorithm is provided as a new technology for solving the difficulties of installing more CCD sensors and filtered back projection reconstruction error caused by limited projection numbers. The radiation intensity projection data got from flame image collected from the installed CCD sensors and computed virtual CCD sensors is interpolated for filtered back projection to computer intensity distribution and calibrated bicolor method is used to calculation temperature in raceway depth direction. The results of experiments on a minitype coal gas furnace and practice test showed that the algorithm is accurate and credible and realized the online monitoring for sudden spread combustion chamber raceway depth direction. At the same time, the useful information is provided for further studying combustion working state for the sudden spread combustion chamber.