A scanning near-field optical microscope (SNOM) based on an apertureless optical probe was presented. The probe had a V shape hollow on its top and coated with metal film. Illumination near-field light (NFL) will emit from the apex of probe when far-field light (FFL) is focused on the hollow. There is a phase difference between collected NFL and FFL, which relates to the distance between probe and sample. The collected FFL can be eliminated using a Glan-Taylor analyzer according to the phase difference. The experimental results show the phase difference of this system is 57°. The spatial resolution of SNCOM is less than 12 nm.