The invention belongs to the field of organic synthesis, and concretely relates to a preparation method of a pyrazolyl acrylonitrile compound. A pyrazole carboxylic ester compound and p-tert-butylphenylacetonitrile are shown in a general formula (II), in the existence of an organic solvent and alkali, a reaction is carried out at 60-160 DEG C, 2-(4-(tert-butyl)phenyl)-1-(1-ethyl-3-methyl-1hydrogen-5-pyrazolyl)-2-cyan vinyl alcohol sodium salt or kali salt is obtained as shown in a general formula (III), a reaction is directly carried out between the obtained compound (III) and pivaloyl chloride at 60-160 DEG C, and the pyrazolyl acrylonitrile compound as shown in a general formula (I) is obtained. The method has the advantages of high yield of the target compound, low 'three wastes (waste gas, waste water and industrial residue)' discharge, and simple operation; and the method is suitable for large scale industrial production.