The hydrolysis process of pentaerythritol diacetals，including influence of reaction rate under different reaction conditions and different substituted groups on the aromatic ring of the reaction substrates，was studied with 1H NMR spectra.With pentaerythritol diacetals as the starting materials，their hydrolysis process was detected in the NMR tube under acidic conditions.The experimental results showed that the hydrolysis rate of pentaerythritol diacetals was increased with the rising of reaction temperature or the acidity of the reaction condition.The electron-donated groups on the aromatic ring of the reaction substrates could accelerate the hydrolysis;However，the electron-withdrawn groups could decelerate the reaction.The reaction rate sequence with the same electron-donated groups on the aromatic ring of the reaction substrates is：para-position＞ortho-position＞meta-position,and the reaction rate sequence with the same electron withdrawn groups on the aromatic ring of the reaction substrates is：meta-position＞para-position＞ortho-position. Therefore，a new method for on-line tracking of the hydrolysis of pentaerythritol diacetals was established.This method has the advantages of speediness and repeatability.The results could provide a theoretical reference for the hydrolysis of pentaerythritol diacetals.