We established a method for quantitative analysis of methyleugenol and safrole in Asarum heterotropoides by GC to study their season variation. The results showed that the content of methyleugenol in the essential oil of the subterranean part of different seasons was 21%-39%, and that for safrole was 17%-33%. In the upterranean part, methyleugenol was 1.4%-9.6%, and safrole was 0.36%-2.1%. It is clear that methyleugenol and safrole are provided mainly by the subterranean part. The quantity of methyleugenol is the richest in the period of sprouting and after-fruiting, and for the safrole content the richest periods are that of sprouting, blooming and after-fruiting. In the case of upterranean part, the richest time is blooming period both for methyleugenol and safrole, and after blooming they decrease gradually.