The invention relates to a digital PCR (Polymerase Chain Reaction) detection device and a liquid path system thereof. The digital PCR detection device comprises a detection chip, a liquid conveying mechanism and a sample conveying mechanism, wherein a diluent channel and a sample channel are formed in the detection chip; the liquid conveying mechanism is used for conveying a diluent into the diluent channel; the sample conveying mechanism is used for conveying a sample into the sample channel; a filtering chip is connected between the sample conveying mechanism and the detection chip; a first filtering pipeline is communicated between the liquid inlet of the filtering chip and the sample conveying mechanism; a second filtering pipeline is communicated between the liquid outlet of the filtering chip and the sample channel. Before being fed into the sample channel of the detection chip by the sample conveying mechanism, the sample passes through the filtering chip firstly, and impurities of the sample can be filtered off by the filtering chip without damaging liquid drops, so that the detection channel of the detection chip can be prevented from being blocked, the replacement frequency of the detection chip can be reduced, frequent focusing can be avoided, the detection efficiency can be improved, and the experiment cost can be lowered; in addition, after impurities and bubbles of the sample are filtered off by the filtering chip, the false judgment probability of an optical system on the liquid drops can be also reduced, and the detection results can be relatively precise.