The invention discloses a self-supporting solid phase support slit width measuring device, and belongs to the field of oil exploitation. The device includes a first guide rod 31 and a second guide rod32 both penetrating through the two ends of a bearing platform 4 and then respectively connected with a top cover 1 and a bottom plate 6, and further comprises a hydraulic device 7 arranged on the bottom plate 6, a pressure gauge 5 arranged on the hydraulic device 7, the bearing platform 4 abutting against the hydraulic device 7, a support agent container 9 arranged on the bearing platform 4, a heating plate 8 positioned on the outer side of the support agent container 9, a temperature sensor 10 arranged on the support agent container 9, a piston 11 abutting against between the support agentcontainer 9 and the top cover 1, and a dial indicator 2 placed on the piston 11. According to the device, the heating plate is used for providing the high temperature environment for the stratum, thetemperature sensor is used for enabling the experimental temperature and the stratum temperature to be consistent, and the dial indicator is used for enabling the measured self-supporting solid phasesupport slit width to be more reliable.