A sensitive DNA biosensor based on dual-amplification of thrombin and thiocyanuric acid-gold nanoparticle (TCA-AuNP) network is developed. First, the sandwich hybridization is formed by the capture probe immobilized on the surface of magnetic beads (MBs), the target DNA and the reporter probe loaded on PbS nanoparticles (PbS NPs). The PbS NPs contain two kinds of DNA sequences, one is the reporter probe complementary to the target DNA, and the other is the thrombin aptamer I. Through the specific recognition for thrombin, thrombin aptamer II labeled gold nanoparticles are linked to the sandwich complex, and further fabricate a network with TCA. AuNPs are released and dissolved into Au(3+), which catalyzes luminol chemiluminescence (CL) reaction. Due to the dual-amplification effects of thrombin-labeled PbS NPs and the TCA-AuNP network, a significant sensitivity enhancement of this DNA biosensor could be obtained, in the range of 2.0 x 10(-16) M to 3.5 x 10(-14) M, with a limit of detection (LOD) as low as 1.0 x 10(-16) M.