(B, ) the utility model relates to a flash distillation separator technical field is a SAGD extraction liquid flash distillation dewatering device, including vertical appearances jar, vertical appearances tank deck end is equipped with out the steam ports, and top -down is equipped with two block at least grid boards in vertical appearances jar upper portion, is equipped with T. P board filler and stainless steel orifice plate ripple filler between two blocks of adjacent grid boards. The utility model has the advantages of reasonable and compact structure, convenient to use, by heating step -down flash distillation makes the liquid phase vaporize fast, light component in the desorption crude oil, it is moisture to reduce crude oil, once only solved low wet crude buffering, separation, broken production difficult problems such as steeping, remove liquid, guaranteed that tower cauldron clean oil is moisture qualified. (B, )