With the advancement of global urbanization, accurate identification of urban functional zones has become a crucial task for the high-quality development of cities. Traditional methods that rely on POI data are insufficient to accurately identify micro-scale urban functional zones. Thus, this study proposes a novel method for identifying urban functional zones based on VOI (Volume of Interest) data and applies it to a small region in Hong Kong for comparative research. Subsequently, the identification accuracy of the two methods is assessed using a confusion matrix and the Kappa Coefficient. The results show that the VOI data contains richer and more comprehensive urban spatial information compared to POI data, enabling a superior representation of connections and influences among different zones within cities. The study can be applied to analyse micro-scale urban functional zones in other cities, providing a new perspective for the in-depth research.