A green, novel, Solvent-free, and efficient method has been developed for the tetra-hydro-pyrimidine derivatives one-pot three-component reaction ethyl cyanoacetate, aldehyde and Urea in the presence of Boric Acid. This method has cyclized various factionalized amines and aldehydes, including aliphatic, aromatics, and heteroaromatic compounds. The cyclisation of ethyl cyanoacetate, aldehyde and Urea these compounds occurred in a single step without any side reaction. The key benefits of this reaction are nontoxic, cheap, environment friendliness and biodegradable catalyst at normal green atmospheric conditions in the absence of solvent. This helps to make the procedure practical, affordable, and biodegradable.