In micro-milling process, the prediction of cutting forces is important for investigating the mechanism of material removal, optimizing the process parameters, and monitoring the machining process. To improve the modelling accuracy, this paper proposes a novel instantaneous uncut chip thickness (IUCT) model that considers the elastic recovery accumulation (ERA) in the micro-milling process. It thus includes the phenomenon of varying IUCT at the current tool tip due to the elastic recovery of the previous tool tip during tool rotation. When the IUCT is less than the minimum uncut thickness (MUCT), the height of the elastic recovery can be increased due to the effect of ERA, while the height keeps constant after IUCT reaches above MUCT. Three cases of ERA are presented by comparing the feed per tooth with both tool runout and MUCT. Finally, micro-milling experiments have been conducted to verify the proposed cutting force model. In comparing with the measured cutting forces, it is shown that the predicted cutting forces with the ERA considered exhibit a much better accuracy than that without the ERA considered. When the feed per tooth is at a small amplitude, the improvement of the cutting force prediction accuracy becomes even more significant.