Abstract: The effects of six surfactants on the basic properties of trypsin were investigated. The results showed that the anionic surfactant sodium dodecyl sulfate greatly inhibited the activity of trypsin, and di-sec-octyl maleate sodium sulfonate dramatically increased the particle size of trypsin solution. Therefore, the two surfactants are not suitable for the leather bating process. Sodium dodecyl benzene sulfonate (SDBS), sodium fatty alcohol polyoxyethylene ether sulfate (AES), alkylphenol polyoxyethylene ether (JFC-1) and fatty alcohol polyoxyethylene ether (AEO-9) had little effect on the activity of trypsin and drastically reduced the surface tension of trypsin solution, but they slightly increased the particle size of trypsin solution. Among the four surfactants, the anionic surfactants SDBS and AES could increase the negative charge of trypsin molecules. Furthermore, the effects of SDBS, AES, JFC-1 and AEO-9 on the mass transfer of trypsin in hide during bating process were studied by fluorescent tracing method. It was found that the four surfactants all obviously improved the transfer rate of trypsin in hide, and the surfactant that had less influence on the particle size of enzyme molecule enhanced the mass transfer more effectively. So, the use of surfactant in bating process is beneficial to shorten the bating time and even reduce the amount of trypsin.