OBJECTIVE To improve the level of HBV-DNA quantity dection.METHODS The necessity and feasibility of quality control improvement on the basis of external quality assessment results were analyzed.The source of error were songht through analyzing the whole experiment process,to improv the experiment protocol.RESULTS Four main sources of error were improved,and two of them existed in reality.Through improvements in handling protocol,coefficient of variability(CV) of internal quality control has decreased to 3.3% from 9.3% before improvement in protocol.External quality control results were also increased in large-scale.CONCLUSIONS Through the improvement in experiment process,quality assurance of HBV-DNA quantity analysis has been upgraded in essence.