The invention provides a self-assembly-colloidal-crystal computer simulation method based on heat-treatment assistance and a preparing method of colloidal single crystals. According to the self-assembly-colloidal-crystal computer simulation method based on the heat-treatment assistance, a physical model for optimizing colloidal crystal technological parameters with the Monte Carlo algorithm is built, and technological parameters such as the optimal self-assembly temperature are simulated and predicted through the physical model; meanwhile, the glue evening method is combined, a plurality of other self-assembly parameters of micro-nano ball crystals are controlled and assembled, and large-area colloidal single crystals are obtained. A theoretical model under the condition that liquid evaporation of the colloidal single crystals is considered is built; based on the theoretical model, computer simulation is introduced, and the efficiency of the self-assembly colloidal crystals is greatly improved; the algorithm of the model is efficient and convenient and fast, quite-large computing resources are not required, the obtained result and the experimental result are highly identical, and the quite-good experiment instruction value and market application prospects are achieved. According to the computer simulation method, multiple codes are specifically adopted in the method; the method for preparing the colloidal crystals is suitable for assembling micro-nano balls with the large-range size, and can also be suitable for assembling different kinds of micro-nano balls.