The invention discloses a landslide early warning method for manual slope cutting in a slate area. The method is characterized by comprising the following steps that a, the slope alpha, area A, upper-side area Au and upper-side slope beta of a landslide body of manual slope cutting in the slate area are investigated, surveyed and mapped on site; b, a topographic comprehensive discriminant factor Tof manual slope cutting in the slate area is calculated according to a formula that T is equal to the sum of S and 1.7U; c, an equivalent rainfall R* and a rainfall factor R are calculated; d, a landslide judgement value P is calculated; e, the landslide judgement value P and a landslide threshold value Cr are subjected to condition discrimination. By means of the method, for manual slope cuttingin the slate area, the internal mechanism of the landslide occurrence degree is studied by studying topographic factors and rainfall factors, the specificity of the slate area and the infiltration characteristic of soil of the slate area are fully considered, an early warning calculation model of slope landslide of manual slope cutting is established, the landslide early warning level is determined quantitatively, and the early warning accuracy is greatly improved.