Abstract: In order to obtain the discharge coefficient (C_d) of the rectangular side weir accurately and efficiently,this paper designed the rectangular side weir model experiment to obtain the experimental values of C_d for six different discharge conditions.The least squares support vector machine (LS-SVM) model with different kernel functions was developed using MATLAB,and the dimensionless parameters affecting C_d were used as model inputs and C_d as model outputs.It is shown that the LS-SVM model can be used to predict the C_d of rectangular side weirs.The mean absolute error (MAE),root mean square error (RMSE) and coefficient of determination (R²) are 0.005,0.005 and 0.966 respectively,which indicates that the model has better performance,higher accuracy and more accurate prediction.An intelligent model for predicting the discharge capacity of side weirs is proposed in this paper,and the influence of different dimensionless parameters on the model is discussed to verify the applicability of the model,which provides a reference basis for similar hydraulic engineering and also provides new ideas for solving complex hydraulics problems.