The invention discloses a deep water oil and gas well overflow monitoring method. The deep water oil and gas well overflow monitoring method comprises the following steps: equidistantly mounting pressure sensors on a water spacing tube according to water depth, measuring circular fluid pressure in the water spacing tube in real time, then transmitting pressure information which is measured by thepressure sensors in real time to a ground control system, and processing and analyzing the measured information of the pressure sensors of the water spacing tube by the ground system to obtain measurement pressure difference between the two adjacent sensors. According to the ground system, drilling fluid is pumped in through a wellhead, the pressure difference between the two adjacent sensors is obtained in combination with a flow and pressure difference relation, the pressure difference measured by the pressure sensors is compared with the pressure difference calculated by the flow and pressure difference relation, overflow in the water spacing tube is monitored and recognized, an alarm is given, and a reasonable well control measure is provided. Underground early overflow monitoring precision is improved, underground early overflow can be recognized in time, the position of overflow fluid in the water spacing tube is determined, the reasonable well control measure is taken, and saferunning of drilling of oil and gas wells is ensured.