The invention belongs to the field of C removal heat-treatment for samples, and in particular relates to a C removal heat-treatment method for the samples of viscosity detection for a crystallizer mould flux. The C removal heat-treatment method for the samples of viscosity detection for the crystallizer mould flux comprises the following steps of: step 1, taking an appropriate amount of samples by a material-holding box, heating to a C removal temperature in a C removal furnace, and then insulating heat; step 2, starting to stir every 10 minutes, after stirring for 3-4 times, stirring every 15-20 minutes, after stirring for 4-5 times, stirring every 30 minutes, and finishing C removal after stirring for 3-4 times, wherein at the moment, the colours of the samples cannot be changed any more. The C removal heat-treatment method disclosed by the invention has the following beneficial effects that: the C removal time for the samples is shortened, the detection efficiency is increased, and then the total detection period for the samples is shortened from the original two batches in three workdays to three batches in two workdays, thus increasing the efficiency by 2.25 times and meeting needs on detection in the field.