Abstract: The strength of solidified/stabilized sludge might be influenced because of the hydrated products decomposed by organic or inorganic acid which came from organic matter degraded for micro-organic activities.Based on the micro-organic activities strengthened by the equipment of bioreactor,the kinetic model for degradation of organic matter and the relationship between the degradation of organic matter and the loss of strength were established.The influence on strength of solidified/stabilized sludge by micro-organic activities could be evaluated by the above model and relationship.It was shown that the influence on strength was existent because of microorganic activities and the influence might decrease with the enhanced level of solidification/stabilization.