Abstract: The G value of the radiolysis products DBP and MBP in TBP-kerosene-HNO3 system was determined using gas chromatographic method. The GDBP is between 1.76 and 2.09 and agrees with that in the literatures; the GMBP is between 0.053 and 0.061 and is about 3 times less than the literature value. The rate constant k of hydrolysis of 30% TBP-kerosene equilibrated with 1 N HNO3 in aqueous phase at 27℃ was determined and found to be 4.36×10-7h-1. Kinetic analysis indicates that there are two ways in forming MBP. MBP is produced not only from DBP, but also from TBP directly. That isTBP→DBP→MBP——H3PO4.Finally, the relationship between the radiolysis products of TBP and the dose absorbed by TBP was given. According to this mechanism the calculated values of GDBP and GMBP agree very well with the experimental values.