Abstract: This paper reported the method for quantitative determination of DNA by the fluorescent dye of DAPI. To make use of fluorimetry detected directly quantity of DNA in the kidenys, livers, spleens, cardiac muscles and skeletal muscles of rabbit to died by ether. And assied the change of DNA quantity following to seven hours for organism.1. The quantity of DNA was not changed following the postmortem in the kidenys, cardiac and skeletal muscles.2. In the spleens, the quantity of DNA was increased following the postmortem.3. In the livers, the quantity of DNA was deceased following the post. mortem.