The producing mechanism and developing law of the temperature restraint stresses on the layer-face of photoelastic model with variable elastic modulus are investigated with experimental studies and theoretical analysis, and the stability of the fringe figure of the restraint stresses or the fixedness of the restraint is verified repeatedly with the experiment. Thus the single model method of eliminating the influence is put forward, and the formula with superposing of fringe parameters of the method is given. The single model method is of great importance to eliminat the influence of the restraint stresses on photoelastic modelling with variable elastic modulus for soil and rock engineering and improving the experiment accurcy.