The invention discloses a method for implementing online tests of 
stream flow based on video images, and belongs to the technical field of non-contact open channel flow measurement. The method relates to a 
water flow tracing 
system, a water surface illuminating 
system, a video flow acquisition 
system, a camera calibrating system, an 
image processing system and a flow estimating system, trace particles are thrown in a flow measuring 
stream segment by the 
water flow tracing system, a camera shoots a water surface video 
stream, frames are extracted at fixed intervals and are processed digitally, the 
image processing system processes digital images according to ground 
control point coordinate information provided by the camera calibrating system, and finally, the 
stream flow is computed by the aid of the flow estimating system according to a flow rate and area method. By the aid of the method, complicity of 
stream flow measurement is reduced, simultaneously, high 
measurement precision can be guaranteed, and the 
stream flow can be dynamically monitored in extreme environments.