Univ Sci & Technol China, Dept Modern Phys, Hefei 230026, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
With the 58 million J/phi data taken at BES II in the last two years, a good particle identification (PID) becomes more important in data analyses. Since BES II TOF is an important subsystem for PID, it is necessary to study TOF time and its resolution in detail. Using the 58 million J/phi data we have studied the corrections for TOF time offset and its resolution, and finaly given out the correction result and PID efficiency.