An　experimental　digital　holographic　microscopy　was　built.　The　focal　plane　was　obtained　automatically　by　Fourier　spectrum　method.　A　method　combining　automatic　phase　aberration　compensation　procedure　with　manual　adjustment　of　the　reconstruction　parameters　was　proposed.　This　method　reconstructed　the　digital　hologram　under　strong　noise.　The　accurate　phase-contrast　image　of　the　test　USAF　target　has　been　obtained.　The　lateral　resolution　was　better　than　2.38　μm　and　the　axial　resolution　was　less　than　10　nm.　The　experimental　results　show　that　under　strong　noisy　background,　the　automatic　phase　aberration　compensation　procedure　must　be　combined　with　manual　adjustment　for　accurate　phase　reconstruction.　This　indicates　the　important　to　record　high　quality　digital　hologram.