Most anurans primarily rely on sound communication for mate choice. To attract females, males might increase the number of syllables or signal complexity to enhance the attractiveness of calls. Working memory refers to memory that involves storing and manipulating information for relatively short time when conducting complex cognitive tasks. Now many studies focus on the functions of the vocal signals, while pay less attention to the effects of working memory on female mate choice and the evolution of complex sexual signals. In this study, phonotaxis experiments were performed to test the working memory of female serrate-legged small treefrogs (Kurixalus odontotarsus, Fig. 1) for different advertisement calls. The treefrogs can produce different calls of graded complexity that contains broadband A note and / or narrowband B note, such as simple advertisement call 5A (a call that contains five A notes) and complex combined calls 5A2B (a call that contains five A notes plus two B notes) / 5A5B (a call that contains five A notes plus five B notes) (Fig. 2). During the experiments, females were exposed to different sound stimulating pairs (5A vs. 5A2B, 5A vs. 5A5B) and then treated with different silent periods (0 s, 5 s, 10 s, 15 s, 30 s) before choosing (Fig. 3). If most females still preferred the speaker that had broadcasted more complex call before, we considered that this silent time was within females’ working memory for more complex call. In addition, the data were processed with generalized estimating equation (GEE) and exact binomial test in SPSS 25.0. As a result, we found that females’ working memory for 5A2B was about 15 s (Fig. 4) and for 5A5B was about 10 s (Fig. 6) compared with 5A, but the comparison between groups showed that there was no significant difference between females’ working memory for 5A2B and 5A5B. The latency of female choosing when broadcasting 5A vs. 5A2B before was significantly longer than that of broadcasting 5A vs. 5A5B before (Fig. 5, Fig. 7). In conclusion, this study demonstrates that working memory of female serrate-legged small treefrogs for complex vocal signals can influence the decision-making of female mate choice, but the effect of working memory on driving the evolution of complex mating signals may be species-specific.