The invention discloses a method for optimization design of hydraulic parameters used for duct tripping-in injection. The hydraulic parameters comprise jet nozzle size and drilling liquid discharge amount of a drilling tool. The method comprises following steps: obtaining design parameters of drilling and stratum soil parameters of an operation region; drawing a design plate of hydraulic parameters; obtaining corresponding undrained shear strength Suo in the maximum stratum when water jet achieves the critical ground-breaking effect based on the design plate of hydraulic parameters and maximum allowable drainage amount of the drilling tool; acquiring undrained shear strength Sumax of the maximum stratum corresponding to the tripping-in depth of duct; determining the size relation between Suo and Sumax in order to ensure the jet nozzle size; and drawing relations between drilling liquid drainage amount and stratum depths in order to ensure drilling liquid amount for stratums in different depth. The method for optimization design of hydraulic parameters used for duct tripping-in injection has following beneficial effects: hydraulic parameters can be directly and quickly obtained on a stratum condition; and the method is applicable to guidance of field operation design and construction and has great applicability.