This study analyzes the factors influencing Vietnamese consumers purchase behavior toward Hai Hau traditional Longan cake, based on an integrated model of S-O-R (Stimulus-Organism-Response) and TPB (Theory of Planned Behavior). The results show that 6 out of 8 hypotheses are supported. Specifically, Perceived Price (PP) and Perceived Quality (PQ) have a positive impact on Attitude (AT), with PQ having a stronger influence; meanwhile, Packaging Aesthetics (PA) is not statistically significant. Simultaneously, Perceived Quality (PQ) and Consumer Ethnocentrism (CE) positively affect Trust in local products (TR). Regarding purchase behavior, both Attitude (AT) and Trust (TR) positively influence Purchase Behavior (PB), with TR exerting a stronger effect, whereas Subjective Norms (SN) are not statistically significant. The research confirms the vital role of perceived quality and consumer ethnocentrism in building trust and driving purchase behavior, while highlighting the mediating role of attitude and trust in the consumption of local traditional specialties. Based on these findings, the study provides discussions and suggests several managerial implications to promote purchase behavior for local traditional products in general, and Hai Hau Longan cake in particular.