The invention discloses a method for measuring the temperature through magnetic resonance, which comprises the following steps: establishing a magnetic resonance temperature model taking fat as a reference object; using a multi-echo gradient-echo sequence to perform image acquisition in the process of heat treatment; using a thermocouple or a thermo-sensitive optical fiber compatible with the magnetic resonance to perform actual temperature measurement for calibration in the stage of the heat treatment or pre-scanning for the first time; acquiring the proton density, the initial phase, the transverse relaxation rate and the resonance frequency after the signal amplitude by a scanner of water and oil by using an expanding Prony algorithm to perform data fitting according to the temperature model; acquiring the oil-water chemical shift according to the resonance frequency of the water and a fat proton; acquiring temperature coefficients alpha and beta according to the oil-water chemical shift and an actually-measured temperature value; and acquiring an absolute temperature according to the oil-water chemical shift and the temperature coefficients alpha and beta. The invention also discloses a device for measuring the temperature through the magnetic resonance. The method and the device can acquire a high-resolution absolute temperature image quickly and greatly and reduce the influence on the temperature measurement accuracy caused by factors of movement, deformation, field floating, fat and the like.