Operating optimization of long-distance water conveyance systems is always intractable for their complexity. In this paper, self-optimization model is introduced to study the problem, which is based on the digital simulation models. Through the on-line optimization tache in it, the decision input can be optimized according to the feedback information of simulating output, so the system can be optimized automatically. With the MATLAB software, simulating optimization of an engineering instance has been achieved, which gives a new way for the research of operating optimization of long-distance complex water conveyance systems.