Objective To examine choroidal thickness and its relationship with axial length and spherical equivalence using spectral domain optical coherence tomography (SD-OCT) in patients with high myopic foveoschisis (MF). Methods Twenty-five patients with MF were prospectively recruited in the Beijing Jingmei Group General Hospital from November 2014 to February 2016. Fifty eyes of 50 age- and sex-matched people were used as controls. SD-OCT was used to measure choroidal thickness subfoveally and at 1.5 mm superiorly, inferiorly, nasally and temporally. A paired t test was used to assess the difference in spherical equivalence, axial length and choroidal thickness between the MF group and the controls. Logistic regression analysis was performed to evaluate the correlation between age, spherical equivalence, axial length, choroidal thickness and MF. Results The differences in spherical equivalence and axial length between the MF group and controls were not statistically significant (P＞0.05). Choroidal thicknesses subfoveally and at 1.5 mm superiorly, inferiorly, nasally and temporally were greater in the controls than in the MF eyes (t=24.131, 20.345, 16.140, 13.923, 19.037, P<0.01) and contralateral eyes (t=22.033, 18.066, 14.818, 13.049, 17.247, P<0.01). The differences were statistically significant. Subfoveal choroidal thickness was less in the MF group compared to the controls (130.3±27.8 µm vs. 147.8±25.6 µm). The difference was statistically significant (t=2.317， P<0.05). Logistic regression demonstrated that decreased choroidal thickness at the subfoveal location was associated with MF (OR, 1.78; 95%CI, 1.39-2.26, P<0.05). Conclusion Subfoveal choroidal thickness was greatly decreased in the MF group, suggesting an association with the mechanism of this disease.