The invention discloses a device for measuring thin-strip casting interface heat flux/heat transfer coefficients and a measuring method. The device comprises a first vacuum chamber, a second vacuum chamber, a rapid transmission mechanism, a heat flux measuring probe, a smelting crucible, an external heating element of the smelting crucible and a thermocouple. The two vacuum chambers are arranged vertically and communicated and a separation plate valve is arranged between the two vacuum chambers. A movable heat insulation baffle is arranged at an inlet inside the second vacuum chamber. The rapid transmission mechanism is arranged on the top of the first vacuum chamber and provided with a transmission rod capable of stretching to the second vacuum chamber from the first vacuum chamber. The heat flux measuring probe is installed on the transmission rod of the rapid transmission mechanism. The smelting crucible and the external heating element of the smelting crucible are arranged in the second vacuum chamber and correspond to the inlet of the second vacuum chamber. The thermocouple is arranged on the measuring probe and connected with a high-speed data collector and a computer through a data line. In an experimental process and in the process of replacing and measuring the heat flux measuring probe, various experimental parameters can still be precisely controlled, the interface heat exchange situation of a base body and molten metal in the thin-strip casting technology is truly simulated, and it is ensured that measured and calculated experimental data are accurate and reliable.