Based on the analysis of the tidal power station operation characteristics， the multi-dimensional optimum operation model is established for the maximum monthly energy output. Linear and nonlinear constraints are involved and the object function is nonlinear for the model. Based on integer mathematical crossover and best individual preservation strategy， an improved genetic algorithm with floating point representation is designed. The model is used to Jiangxia Tidal Power. After the comparison with the actual maximum monthly energy output and the result of dynamic programming method， it can be seen that the model is reasonable and effective.