To meet the requirements of China Ⅵb lightduty vehicle emission regulations for nitrogen oxides (NO_x) and particulate matter (PM), the selective catalytic reduction particulate filter (SDPF) was developed for a given light-duty diesel engine. Under urban driving and idle conditions, regeneration efficiency is low, which increases the risk of SDPF blockage and even thermal damage. To address this problem, the identification logic under idle and idle and urban condition transformation was constructed. Then an accurate estimation of SDPF soot load was used as a key input for triggering idle regeneration based on differential pressure and flow resistance models, therefore an SDPF idle regeneration control strategy was developed. Real-vehicle testing validated the effectiveness of the idle regeneration control strategy under the states of deceleration to idle, idle and idle to urban driving. The results show that a significant improvement in regeneration efficiency, which proves the effectiveness of the SDPF idle regeneration control strategy and improves the safety of SDPF operation.