The invention relates to an automatic sampling device for testing the fluidity of indoor crude oil. The bottom of a sampling cylinder (4) and a switch body (15) are connected through screw threads; the switch body (15) is positioned in a hole sleeve (18), passes through an oil nozzle (13) of an oil sample and is connected and fixed with the outside of a simulation tank (1) through screw threads; the upper part of the sampling cylinder (4) runs through an open hole of a sealing cover (2) of the simulation tank and is fixed with the sealing cover (2) of the simulation tank through a connecting flange (5) with an exhaust port; a step electric bolt (8) of a step motor (6) is connected with a screw rod inner cylinder (9) through a fixed bolt (7); the screw rod inner cylinder (9) is connected with a piston (11) through a connecting rod (10); the step electric bolt (8), the fixed bolt (7), the screw rod inner cylinder (9) and the connecting rod (10) form a transmission mechanism of the device; the transmission mechanism is positioned in the sampling cylinder (4); the step motor (6) controlling the transmission mechanism is connected and fixed with the connecting flange (5); and the bottom of the sampling cylinder (4) is provided with an oil nozzle switch device (14) consisting of a self-power type spring and steel beads.