The invention discloses a device and method for detecting the bleeding amount in real time. The device comprises a haemoconcentration detecting unit based on infrared signal detecting, a flow detecting unit, a data processing unit and a displaying unit. The haemoconcentration is automatically collected based on the linear relation between the haemoconcentration and a voltage signal; based on the data collection and electric signal conversion of the flow detecting unit, a bleeding amount measuring module can be used for calculating the current bleeding amount according to an instant haemoconcentration signal and an instant flow signal, and the total bleeding amount is obtained based on accumulation calculation; the total bleeding amount is displayed through a displaying device, a scientific and accurate basis can be provided for bleeding amount judgment in a clinical operation, and a man-made estimated error is avoided.