The invention provides a traditional water purification process based land saving reconstruction upgrade method which comprises the following steps: (1) lake or reservoir raw water enters into a water pump room by a sodium hypochlorite dosing device; (2) the lake or reservoir raw water then enters into a water work coagulating pool by a pre-ozonation and coagulant dosing device; (3) the lake or reservoir raw water then enters into an immersion-type PVDF (polyvinylidene fluoride) ultrafiltration membrane suction component by a horizontal sedimentation tank; (4) the lake or reservoir raw water then enters into a particles crushing activated carbon-quartz sand double-layer filter to be sequentially disinfected by Uv-chloramines, then enters into a clean water tank, and then is sent to a water distribution pipe network by pressurized conveying. The traditional water purification process based land saving reconstruction upgrade method is an improvement to a traditional water purification process, can achieve a fundamental improvement of the water quality, and has the advantages of being simple, compact in process, low in cost and obvious in effect.