A cold start-compatible urea SCR system using an exhaust gas purification device, the exhaust gas purification device including a diesel fuel injection means, a DOC, a lean NOx trap release material (LNTR), a urea water injection means, an catalyst of selective catalytic reduction (SCR), and a measurement and control means, the DOC and LNTR being supported on a support in an upper-lower or a front-rear divided manner, the DOC being located in an upper layer or a lower layer, or on a front side, the LNTR being located in an upper layer or a lower layer, or on the rear side.