The invention discloses a dynamic and static triaxial tester for frozen and thawed soil in an open system. The tester comprises a temperature control system, a water-replenishing system, a loading system, a confining pressure system, and a data acquisition system, wherein the temperature control system comprises a cold end socket, a warn end socket, a high and low-temperature constant-temperature liquid bath circulator, a porous pressure-transmitting medium, and a rubber film; the water-replenishing system comprises a water-replenishing tank, a water-replenishing bottle, and a high-intake value ceramic plate; the loading system comprises an exciter, a reaction frame, a test pedestal, a central force transmission rod, and a counterweight; the confining pressure system comprises a linear bearing, a pneumatic valve, an external pressure chamber, and an internal pressure chamber; and the data acquisition system comprises a displacement sensor, an annular liquid level calibration chamber, a dilatation measurement chamber, a differential pressure sensor, a piezoelectric force sensor, a temperature sensor, and a humidity sensor. The dynamic and static triaxial tester for the frozen and thawed soil in the open system disclosed by the invention can carry out a conventional frozen soil test involved in Code for Soil Test of Railway Engineering (TB10102-2010), an unidirectional freezing or thawing test for a specimen under the action of a dynamic load and different stress states, etc.