Abstract: The main design coefficients of pools' baly and control factors in the half anaerobic process were studied. This half anerobic pool was thought belongs to the upflow mud bed,and it has good treatment and good lower investment with circular pool body and circular well-distrbutied water For the reason of the live reactive ratio k near to the theory reactive ratio k, we must manage scientifically the factors:pH T HRT,nutirtion-balance of sewage in reactive pool