The charge-carrier mobility of the blend films consisting of organic small molecule and quantum dots (QDs)，Alq3 and CdSeS，are studied by time-of-flight (TOF) technique. The dependence of charge-carrier mobility in the blend films on electric filed and QD concentration is measured. The results show that the positional disorder in the blend films are increased with the increase of QD concentration. Moreover，the charge transport mechanisms between Alq3 and QDs and the number of electron hoppings between QDs will lead to the change of the charge-carrier mobility.