In order to solve the problem of poor appearance and low external pressure within current precast components, concrete mixture ratio is studied through experiments, which takes U-shape drainage trough as an object to dig into the effects of different mixture ratio on concrete appearance, external pressure and anti-permeability, the connection between concrete workability and strength with U-shape drainage trough appearance and external pressure is also discussed. To cast U-shape drainage trough with good performance, a reasonable concrete mixture ratio was given, reasonable range of concrete VC values and strength were also determined. It could be of certain reference value for casting drainage trough components.