The invention provides a method for detecting a low-taper circular conical surface. By the method, the low-taper circular conical surface can be precisely detected in real time and a workpiece to be detected is not damaged during processing, and the problem that a detection result is not matched with data which is measured by a coordinate measuring machine is solved. The method comprises the following steps of: cutting out two sections which are away from a Z plane by different distances on a circular conical surface solid of the workpiece to be detected; producing a special stop-pass caliper gauge according to the design tolerance requirements of section contour circles which are taken as detection objects; and detecting the two corresponding section contour circles on the circular conical surface solid of the workpiece to be detected by the special stop-pass caliper gauge, wherein if the two section contour circles can respectively pass through a go end of the special stop-pass caliper gauge and are limited by a not-go-end of the special stop-pass caliper gauge, the low-taper circular conical surface is judged to be qualified. The whole special stop-pass caliper gauge is in the shape of reversed C; the whole thickness of the special stop-pass caliper gauge is equal to the distance between each section to be detected and a detection reference surface; an upper edge and a lower edge of a C-shaped opening of the special stop-pass caliper gauge are parallel in the horizontal direction; a go-end limit edge is arranged at an outer side end of an inner wall of each of the upper edge and the lower edge of the C-shaped opening of the special stop-pass caliper gauge; and a not-go-end limit edge is arranged at an inner side end of each go-end limit edge.