Microemulsion exhibits significant application potential in low-permeability reservoirs owing to its superior capabilities in reducing oil-water interfacial tension，altering wettability，enhancing solubilization，and maintaining thermal stability. Taking the low permeability reservoir in Block Chang-3 of Changqing oilfield as an example，the reservoir adaptability of the field application of microemulsion system was systematically evaluated by means of microemulsion micromorphology measurement， particle size analysis，interfacial tension measurement，crude oil component solubilization and wettability test，and its oil displacement potential was explored by means of nuclear magnetic resonance online displacement system. The experimental results demonstrated that the microemulsion exhibited an oil-in-water（O/W）structure with an average particle size of approximately 13 nm，which could effectively match with the micro-nano pore throat of low permeability reservoir. Notably，this system achieved significant interfacial activity，reducing oil-water interfacial tension to 1.71 mN/m，while the interfacial modulus increased with rising oscillation frequency. After 20 days of aging at the reservoir temperature，the key parameters including particle size and interfacial tension kept stable，while the microemulsion demonstrated exceptional solubilization capacity with an oil solubilization parameter reaching 36 mL/g，particularly，the enhanced solubilization effects were observed for saturated and aromatic fractions. Furthermore，the system effectively altered reservoir wettability，as evidenced by the substantial decrease in underwater oil droplet contact angle from 164° to 55° ，indicating a successful transition from oil-wet to water-wet conditions. The nuclear magnetic resonance online flooding experiments further revealed that injection of 1.0 PV of the microemulsion enhances oil recovery by 10.86 percentage point while reduced displacement pressure by 24.87% ，demonstrating significant pressure reducing and injection enhancing effects. The experimental results revealed that the microemulsion system exhibited considerable potential for enhanced oil recovery，providing crucial technical support for its large-scale field application in low-permeability reservoirs of Changqing oilfield.