The invention relates to a Marshall stability tester with an automatically elevated upper pressure head. The tester comprises a main machine connected with a power source; a motor is arranged in the main machine, and the upper surface of the main machine is provided with a base plate; the motor is connected with the base plate through a conductive wire; a support has a door-shaped shape, and is arranged across the base plate; the center of the bottom of the upper pressure head is provided with an arc-shaped concave, the center of the top of a lower pressure head is provided with an arc-shaped concave, and the arc-shaped concaves form a ring; grooves are arranged at two sides of the bottom of the upper pressure head; vertical channels are drilled at two sides of the lower pressure head and are used for sleeves to penetrate, and the middle of the bottom of the lower pressure head is provided with a support pad; the base plate can support and lift the sleeves and the support pad; one ends of elevating rods are arranged in the sleeves, and are connected with conductive wires, and the other ends traverse through the sleeves and enter the grooves; the conductive wires connect the base plate with a control system. Every conductive wire is wrapped with an insulating sheath; every conductive wire is made of alloy copper; and every insulating sheath is made of a polyimide paint or an acetal paint. An insulating material involved in the invention is more light and wear-resistant than materials in the prior art.