The invention provides a measuring method of the liquid full pressure gradient-flow relation in a low-permeability reservoir. The measuring method includes the steps that 1, a thin glass tube communicator device is adopted for measuring the static starting pressure gradient in a low-permeability rock core; 2, a multifunctional rock core displacement device is adopted for measuring the steady state pressure gradient-flow relation; 3, the starting pressure gradient, obtained through the static method, of the low-permeability rock core and the steady state pressure gradient-flow data obtained through measurement by the steady-state method are drawn in the same graph, and then the liquid flowing full pressure gradient-flow relation of the low-permeability rock core is obtained. By means of the measuring method of the liquid full pressure gradient-flow relation in the low-permeability reservoir, the starting pressure of the low-permeability rock core can be measured accurately, the liquid flowing pressure gradient-flow relation can be obtained on the basis of the full pressure gradient, and the obtained flow characteristics of the low-permeability rock core are more accurate and can be used for flowing characteristics description of the low-permeability reservoir.