Objective To explore the effectiveness of whole genome amplification technology in DNA typing of trace samples.Methods Simulated trace samples which contain 1～20 cells were prepared by micromanipulation.Whole genome amplification was added before conventional PCR-STR typing step,to compare the effectiveness of PEP and MDA in DNA typing of trace samples from four aspects i.e.allele imbalance,allele drop-out,locus drop-out and pseudo allele (which contains the stutter peak).Results Amplification efficiency of MDA was higher than PEP method,but allele drop-out and pseudo allele were more frequently detected.Correct DNA typing rate of PEP is higher than MDA method,however,advantaged amplification of small fiagments DNA is more obvious.Conclusion MDA method is not suitable for the current STR typing.When the absolute amount of trace samples is quite small,we couldconsider using the PEP method to enhancethe sample quantity to meet the requirement of repeat testing.At the same time it could encounterthe failure of the large DNA fragments.