The invention discloses a capillary flow noise analysis and structural transformation design system, which comprises the following steps of S1, building a parameterized model of an outlet of a capillary; S2, starting an optimization flow; S3, calculating a one-dimensional mathematical model of the capillary, giving import and export conditions of an outlet end of the capillary, calculating a simulation result of fluid mechanics to obtain flowing information, adopting the information as an input condition for calculating acoustic analysis, carrying out accurate sound field simulation, and adopting a final result of acoustic analysis as a noise assessment target of a current capillary structure; S4, optimizing an algorithm; S5, judging whether a noise structure meets an optimal target value or not, if yes, adopting the noise structure as an optimal result and outputting, if not, returning to the S4 step for re-optimizing the algorithm until the noise structure meets the optimal target value, and completing the result output of the whole system. The invention provides a universal, accurate and low-cost capillary noise reduction improvement system independent of people, and achieves the aim of engineering application.