improved rate equations are established for the new model of index-crossover gain guided-index antiguided (igg-iag) fiber, then the pump and signal light power distribution along the igg-iag fiber are investigated. based on the thermal conduction equations, the 3d temperature distributions of a one-end-pumped and dual-end-pumped nd3+-doped igg-iag fiber laser are further analyzed. the simulation results show that many factors have an important influence on fiber temperature. the temperature of the fiber with the dual-end-pump method is obviously lower than that with the one-end-pump method, and the temperature distribution is more uniform. the larger the r value, the lower the fiber temperature, and the smaller the -delta n, the lower the fiber temperature. thus proper fiber parameters and pump scheme may help to reduce the fiber temperature.