In order to find high biological active pesticide, eighteen novel aroyl thioureas and aryloxyacetyl ones have been synthesized by the reaction of 5-amino-1,3,4-thiadiazol-2-carboxylic acid with aroyl isothiocyanates and aryloxyacetyl isothiocyanates, with their structure confirmed by IR, 1H NMR spectra and elemental analysis. The preliminary biological activity tests showed that some title compounds have good activity as plant growth regulator, ...