Imbibition is one of the important oil recovery mode for the tight oil reservoir. Imbibition mechanism between the fracture and the matrix was studied thoroughly，but there is no agreement on the influence and contribution of imbibition and displacement on the recovery degree in the seepage stage. Therefore，based on the pore structure distribution characteristics and the pressure characteristics of the fracture system and matrix system of Chang8 tight oil reservoir in Shuimogou area of Yanchang Oilfield，NMR technology was used to quantitatively characterize the influence of displacement method and imbibition method on the recovery degree and the distribution of movable fluid. The experimental results show that the main controlling factor on the seepage ability of the tight oil reservoir in the study area is the throat radius；the recovery degree of the matrix system in the fractured core samples is mainly controlled by the imbibition，and the recovery degree of the fracture system is mainly controlled by the displacement. The recovery of the displacement and imbibition methods based on NMR quantitative analysis was 32.30%-39.32% and 9.60%-19.49% respectively. The microscopic pore structure of the core samples in the tight oil reservoir is complex，and the flow direction of the fluid during the process of imbibition and displacement is affected by the wettability of the microscopic pore throat，so the distribution of the movable fluid obtained by the imbibition and displacement method has no strict pore size boundaries.