The invention provides a water separation and collection control method and a device and a floor heating supply system, and can solve the unit stop caused by excessively lower water flow of the system. The water separation and collection control method comprises the steps of: determining an ith water way as a normally open water way or a closeable water way when receiving an ith water way closing signal, wherein i is not smaller than 1 and not bigger than N, and is an integer, and N is a total number of water ways in the floor heating supply system; outputting an ith water way opening signal if the ith water way is the normally open water way; determining if the total number of the present opened water ways besides the ith water way is bigger than the minimum number of the water ways needing to be opened in the floor heating supply system if the ith water way is the closeable water way; if so, outputting the ith water way closing signal; and if not, outputting the ith water way opening signal. The water separation and collection control method is suitable for the technical field of heating.