Interaction effect of CaCl2 and complex activator（composed of CaCl2 and sodium silicate glass） on the Yellow River sediment was investigated in terms of parameters, such as pozzolanic activity index（PAI） of sediment mortars, activity ratio（K） of activated sediment, compressive strength and softening coefficient of sediment based soil blocks. Activation mechanism can be elucidated by FTIR and XRD analysis of sediment before and after activated. Results show that the reaction activity of sediment is significantly improved by complex activator when the mass ratio of CaCl2 and sodium silicate glass is 1∶1. PAI of activated sediment reaches 063 when the content（by mass） of complex activator is 6%. CaCl2 promotes the release of soluble Si4+ and Al3+ by ion exchange of Ca2+ with Na+. Thus，the reaction activity of the Yellow River sediment and the mechanical properties of sediment based soil blocks will be improved.