Potassium dinitroacetonitrile was synthesized via the reactions of nitrosation and nitration-hydrolysis using ethyl cyanoacetate as raw material with a total yield of 76.93%, and its structure was characterized by NMR, IR and elemental analysis. The samples of potassium dinitroacetonitrile with different crystal morphologies were prepared by adding the different surfactants, changing the cooling rate and stirring speed. The thermal decomposition process of potassium dinitroacetonitrile with different crystal morphologies was studied by DSC and their mechanical sensitivities were tested. Results show that the crystal morphology of potassium dinitroacetonitrile has little effect on the thermal decomposition process of the sample. The sensitivity of potassium dinitroacetonitrile sample obtained after the addition of surfactant polyethylene glycol (400) is the lowest (the impact sensitivity is 8%, the friction sensitivity is 12% and the characteristic drop heights of impact sensitivity H₅₀ is >129.5 cm).