The magnetization measurements of Hg0.89Mn0.11Te sample grown by vertical Bridgman method have been carried out at 5 K under external field from -5200 to 5200 kA/m, and at 800 kA/m from 5 to 300 K with zero-field-cooling and field-cooling respectively using the superconducting quantum interference device (SQUID) magnetometer. Based on the mean field theory, a modified Brillouin function is well fitted with the data of magnetization vs magnetic field over the entire magnetic field range. The analysis indicates that there is an antiferromagnetic exchange coupling between Mn ions. The results of reciprocal susceptibility vs temperature show Curie-Weiss behaviors at temperatures above 40 K and a deviation from the Curie-Weiss law at temperatures from 5 to 40 K, which shows that the antiferromagnetic exchange coupling between Mn ions increases with decreasing temperature. The result was explained by extending higher-order terms in the calculation of susceptibility. Hg0.89Mn0.11Te is a paramagnetic material in temperature range from 5 to 300 K.