The commutator and brush of the motor are often worn during operation. The wear of commutator—brushes is influenced by various factors: current density, material, sliding speed, contact force, temperature, and environmental humidity, especially by humid tropical climate conditions. This affects directly wear, long life, and the reliability of commutator—brushes. This paper presents the results of the electrical sliding wear behavior of the graphite brushes when the temperature, the humidity of the humid tropical environment, and current change. According to experimental planning, the studies were conducted on graphite brushes with three input factors: the temperature of 25 °C, 40 °C, and 55 °C, relative humidity (RH) of 51%, 75%, and 99%, and current 5 A, 7.5 A, and 10 A. The results show that the specific wear-rate Ws increases when relative humidity, temperature, and current increase. When the brush works in extreme conditions, the specific wear-rate Ws will reach the maximum value and equal to about 5.37 times the Ws value in the best conditions in this experiment.