The invention relates to a method for determining the stability of a liquid accelerator. The method comprises the following steps: 1, preparing a liquid accelerator sample with the mass concentration of 35-50% for later use; 2, weighing the standby sample, allowing the sample to stand at a low temperature of -10-5DEG C for 8-12h, allowing the sample to stand at 18-26DEG C for 3-5h, and standing the sample in a 80-85DEG C oven for 6-10h; and 3, repeating step 2, standing, observing the layering or precipitation condition of the sample, and analyzing the stability of the liquid accelerator. The method allows the stability of the liquid accelerator to be tested within a short time, and has the advantages of high test precision, simplicity, convenience, shortening of the optimization cycle of liquid accelerator technologies, and great improvement of the working efficiency.