The invention provides a preparation method of a phenylacetylene liquid crystal material, which is shown in the formula I. The phenylacetylene liquid crystal material is prepared through the following steps, comprising, 1) synthesis, including in a first organic solvent, heating a compound shown in the formula II, a compound shown in the formula III and alkali in the action of a catalyst for a sonogashira reaction shown in the description, wherein R1 is -F or -NH2, R2 is alkyl having 3-7 carbon atoms, unsaturated alkyl having 3-7 carbon atoms, or alkoxy having 3-7 carbon atoms, L1 and L2 are H or F, respectively, m is 0 or 1, X is -Cl, -Br, or -I, and a structure shown in the description is cyclohexylidene, phenylene, or 2,4-disubstituted pyrimidine; and 2) purification, including purifying the reaction product obtained in the step 1) with a soxhlet extractor after the sonogashira reaction is finished. The preparation and purification method of a phenylacetylene liquid crystal material is simple in instruments, convenient to operate, saved in time, high in purity and less in loss.