The invention relates to a 
reconstruction method for a 
hearth three-dimensional temperature field. The method comprises the following steps that: a burning 
flame colorized image can be obtained through a CCD (
Charge Coupled Device) image 
pickup system and a 
computer processing system, based on R,G and B pixels of a 
flame image, two-dimensional temperature of a burning 
flame image can be obtained through a neural network BP 
algorithm, an inverse solution of a 
radiative transfer equation can be combined, and three-dimensional temperature distribution of a burning flame in a 
hearth can be further obtained. The 
reconstruction method has the advantages of scientific design and creativeness, three-dimensional characteristic of 
coal dust in a large-scale boiler can be fully embodied, and the 
reconstruction method is significant to safety, economic benefit, clean operation and the like of the boiler. The 
system disclosed by the invention has the advantages of compact structure, less 
material consumption, long service life, stable and reliable performance, convenient for maintenance and high 
measurement precision of three-dimensional temperature, and flame 
combustion condition in the boiler can be controlled in time.