The invention discloses an in-situ observation testing device for simulating a micro oil displacing interface. The in-situ observation testing device comprises a base, a runner 
test sample movement component, a runner 
test sample component, an oil displacing component, a 
microscope movement component, a 
microscope component and a control acquisition component, wherein the runner 
test sample movement component comprises a 
servo motor, a first 
roller screw rod and a first screw rod screw nut; the runner test sample component comprises a support platform, a 
temperature control device and a test sample group; the oil displacing component comprises a 
peristaltic pump, a displacement liquid 
reagent bottle, 
inlet pressure acquisition equipment, outlet pressure acquisition equipment, volume 
measuring equipment and a weighing balance; the 
microscope component comprises a microscope lens, a microscope support component and an 
image acquisition device; the control acquisition component is used for acquiring image data and for acquiring and analyzing pressure, volume and 
mass data, and for controlling the movement of the 
servo motor and the flow of the 
peristaltic pump. By adopting the in-situ observation testing device, the interaction of micro surfaces and interfaces among different displacement liquids, 
crude oil and runners in the 
crude oil exploration process can be simulated, and study on oil-displacement mechanisms can be promoted.