Abstract: The emission characteristics of particles with particle sizes above 23 nm （PN₂₃） and above 10 nm （PN₁₀） were analyzed under steady-state and transient conditions of the non-road regulatory test cycle， using a small-power diesel engine equipped with a diesel particulate filter（DPF）. The results show that the emissions of particles in the size range of 10 nm to 23 nm （hereinafter referred to as PN_10~23） cannot be neglected under both steady-state and transient test cycles， and cold-start processes have a more significant impact on the emissions of particles within the size range. The DPF demonstrates high filtration efficiencies for both PN₂₃ and PN₁₀， remaining an effective technology for reducing particle emissions across different sizes. In the hot steady-state cycle， the exhaust gas temperature has substantial influence on the emissions of PN_10~23， and the high-temperature and low-flow condition has the greatest influence on PN_10~23 emissions. The cold start process in the transient cycle affects both PN₂₃ and PN₁₀ emissions， but its impact on PN₁₀ emissions is more pronounced. Cold start conditions significantly increase PN₁₀ emissions during the initial stage of the cycle. Due to the low exhaust temperature during the cold start process in the transient cycle， PN_10~23 emissions are significantly increased.