Living roots and its rhizodeposition can stimulate or retard soil organic matter (SOM) decomposition via the rhizosphere priming effect (RPE). However, little is known about the RPE during non-growing seasons. In this study, we measured the RPEs of two perennial grasses (Elymus dahuricus, Stipa grandis) and two legumes (Medicago sativa, Melissilus ruthenicus) after leaf senescence and before shoot regrowth using a ¹³C natural tracer method. All four species produced positive RPEs at each sampling time, with the magnitude ranging from 40% to 238% compared to unplanted soil. Further, the inter-specific variation in the RPE during the non-growing season was partly explained by the root:shoot ratio, average root diameter and root tissue density. Overall, these results demonstrate that live roots of non-woody perennials could accelerate SOM decomposition even during the non-growing season.