A spatiotemporally resolved far-field pulse contrast measuring device includes a plano-convex cylindrical lens, a nonlinear correlation crystal, a plano-convex imaging lens and a signal-receiving system. The signal-receiving system includes a fiber array, a photomultiplier and a digital oscilloscope. A measuring method of the device includes steps of: focusing an under-test beam in x dimension to make a focus of the under-test beam fall onto a front surface of the nonlinear correlation crystal; making a spatial correlation and a temporal correlation respectively in two transverse spatial dimensions (x-y) of the nonlinear correlation crystal by the far-field under-test beam and a sampling beam; generating a two-dimensional correlating signal by the spatiotemporal correlation; imaging the two-dimensional correlating signal by an imaging system onto a detection surface of a receiver system; and measuring the x-dimensional and y-dimensional intensity distributions of the correlating signal highly dynamically by the receiver system.