Discharge coefficients are investigated with five inclined multi-hole test plates of different geometrical configurations. The physical nature and influential factors of discharge coefficients are considered.The results show that the momentum ratio I1 and Renolds mumbers of little holes have important effect on discharge coeffcients but momentum ratio I2 has no influence.Parameters of the geometrical configuration P/D

S/D

α

β and L/D have great influence

but the rows of holes has little effect on discharge coefficients.