In large flow water conveyance projects, strong pressure fluctuations often occur along the pipeline after pump failure, which is likely to cause low water level pressure down the pipeline. In this paper, the mathematical model of a throttled surge chamber with a connecting valve was proposed based on the actual situation of a large flow water conveyance project, and the water hammer protection characteristics of three kinds of chambers, which are simple surge chamber, throttled surge chamber and throttled surge chamber with a connecting valve were compared and analyzed. The superiority of the throttled surge chamber with a connecting valve was verified, and the effects of the valve closing pattern on the water hammer protection of the surge chamber were studied. The research shows that the water hammer protection effect of the throttled surge chamber with a connecting valve is superior to that of the simple surge chamber and the throttled surge chamber. It can effectively increase the minimum water level of the chamber and the minimum pressure along the pipeline with less space needed. When the pump is powered off, the connecting valve should be turned off as early as possible, preferably choosing the primal closing rate.