In this paper, a precise transverse micro-segment tooth profile is established. Subsequently, a load distribution model of micro-segment gears is proposed based on the method of elastic potential energy. A method for choosing an equivalent base circle is proposed to accurately calculate the tooth force of each tooth pair of spur micro-segment gears. Similar to spur gears, a torque distribution method is also established for helical micro-segment gears. Based on the simulation analysis of different basic micro-segment parameters, their significant influence on the load distribution is presented. In addition, it is found that during an entire contact period, the maximal tooth force of a micro-segment gear pair is smaller than that of an involute gear pair. The model is also validated by the finite element method. This model provides a rapid and effective approach to determine the load for the subsequent analysis of the contact and bending strengths of micro-segment gears.