法兰西斯式水轮机（英语：Francis turbine），又称混流式水轮机，是由美国马萨诸塞州洛厄尔的詹姆斯·B·法兰西斯所开发。此种形式的水轮机是利用水流的压力和动能来带动轴上的扇叶同心圆转动来做功。

法兰西斯式水轮机是现今最广泛受到采用的一种水轮机形式，此水轮机可在水头高度40～600米（130至2,000英尺）之间运作，其最常见于水力发电时所使用。而此种形式所带动的发电机，其发电的输出电力范围从几千瓦到800万千瓦，而更小的水力发电机其电力输出范围将可能会更低。水力动能来源的压力钢管（输入管道）设计直径为3和33英尺（0.91和10.06米）之间，转速范围从75到1000转。旋闸环绕在水轮机旋转流道外围，以控制水流通过水轮机流速的方式来控制不同的电力生产率。

The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts.

Francis turbines are the most common water turbine in use today. They operate in a water head from 40 to 600 m (130 to 2,000 ft) and are primarily used for electrical power production. The electric generators which most often use this type of turbine have a power output which generally ranges just a few kilowatts up to 800 MW, though mini-hydro installations may be lower. Penstock (input pipes) diameters are between 3 and 33 feet (0.91 and 10.06 metres). The speed range of the turbine is from 75 to 1000 rpm. Wicket gates around the outside of the turbine's rotating runner control the rate of water flow through the turbine for different power production rates. Francis turbines are almost always mounted with the shaft vertical to isolate water from the generator. This also facilitates installation and maintenance.