Abstract: In order to explore a reliable model, we must eliminate the errors of the modeling surveying points firstly. Because of the brainpower and robustness for parameters exploring, the principle of information diffusion is naturally used for exploring the reliable model. This paper analyzes the probability that some of the factor weights can be determined by the principle of information diffusion, deduces a series of statistics to the scale and angle during the course of the modeling, and brings forward a reasonable method for judging the model reliability of the plane similitude conversion by using the approximate t-test. Lastly, the operation process about the model reliability is analyzed, on the basis of the example of the model optimization which was used for Xiaodongjiang GPS metamorphose monitoring network.