Abstract: A numerical model of the thin composite disk side-pumped by ring laserdiode array (LDA) is set up. The LDA fast axis is upright to the disk surface and is compressed. The distribution of the pump, temperature and thermal stress in the thin disk is calculated by a finite element method and the influence of pump power, heat transfer coefficient and time on the temperature and thermal stress is analyzed. Results of simulation indicate that thermal extendable destroy appears on the edge of the composite surface. The rise time and recovery time of the temperature and stress show no obvious change as the pump power increases, while they decrease along with the increase of the heat transfer coefficient. The steady temperature and thermal stress of temperature correlation considering the thermod