An indoor simulation experiment was carried out to study effects of monochlorobenzene on activities of three major hydrolyzable soil enzymes (urease, invertase and phosphatase). Results showed that the three enzymes had ativities within the range of 20.81～162.00μgg^-1h^-1, 64.60～582.10μgg^-1h^-1 and 5.80～89.75μgg^-1h^-1 separately when the monochlorobenzene was in the designed concentration from 5.53 gkg^-1 to 110.58gkg^-1, which stimulate soil urease activity, while inhibit soil invertase and phosphatase activities by 1.11%～118%, 0.74%～25.43% and 2.02%～35.63%, respectively. It indicated that the three soil enzymes could be used to a certain extent as indicators of soil pollution by monochlorobenzene. The reaction style of soil phosphatase with monochlorobenzene obtained from regression equation of U =B/ ( 1 +A x ) was full inhibition. The monochlorobenzene concentrations that may characterize slight pollution of Lou soil and red soil were 33.9 g kg^-1 and 16.7 g kg^-1.