Micromixing efficiency is an important parameter for evaluating the multiphase mass transfer performance and reaction efficiency of microreactor. In this work, the novel curved capillary reactor with different shapes were designed to generate Dean flow, which was used to enhance the liquid–liquid micromixing performance. The Villermaux–Dushman probe reaction was employed to characterize the micromixing performance in different curved cpillary microreactor. The effects of experiment parameters such as liquid flow rate, inner diameter, tube length, and curve diameter on micromixing performance were systematically investigated. Under the optimal condition, the minimum value of the segmentation factor XS was 0.008. It was worth noting that at the low Reynolds number (Re < 30), the change of curved shape on capillary microreactor can significantly improve the micromixing performance with XS reduced by 37.5%. Further, the correlations of segment index XS with dimensionless factor as Reynolds number or Dean number were developed, which can be used to predict the liquid–liquid micromixing performance in capillary microreactor.