Nineteen samples of crystalline zircon from 5 gr:3.nitic bodies of two genetic types (syntexis type and transformation type) irn Nanling region have been studied with the aid of infrared-spect}m. The following results are- obtained: 1. The kurtosises of the absorbtion peaks of zircons at 612cm-1 and 900- 1OOOcm-1 (two peeks) in syntexis-type (I type,) granites are much stronger than those in transformation-type (S type) granites. 2. The Δ612(H/W)ratios of zircon ranges 27-36 in the syntexis type and 6.5-22 in the transformation type. 3. The Δ900-1000 ratios of zicon is>1 in the syntexis type but<1 in the transformation type. 5 .The peaks of H20 of zircon in the transformation type is stronger than that in the syntexis type. 6 .The frequency(γ)of zircon in the syntexis type is higher than that in the tsansfozrnation type with adifferenece of 4-12cm-1. 7 .The REE and U+Th contents in zircon in the syntexis type is lower than those in the transformation type and there is negative correlation between the contents of there elements with the values of Δ612 and T612. The charactezistics above-mentioned can be regarded as new criteria foz distinguishing the genetic type of granitic rocks, based on which the Xiling tin- (copper-) beating quartz dioritic porphyrite in Guangdong province can be referred to the syntexis-type.