Abstract: In order to analyze the feasibility of corner-pumped method in medium and small power lasers design,ray-tracing algorithm was used to simulate the pumping efficiency and absorbed energy distribution of diode corner-pumped lasers for different laser medium parameters and different diode temperatures.It is concluded that high pumping efficiency and good pump uniformity can be obtained for corner-pumped composite slab lasers with appropriate choice of laser medium parameters.A diode cornerpumped composite Nd:YAG slab laser was designed, whose output power was up to 12W under the pump power 45W at opticaloptical efficiency of about 26.7%,and whose M2 factors of beam quality at width and thickness direction were 1.47 and 1.36 respectively at 40W pumping energy.Theoretic; analysis and experimental design show that corner-pumped method is useful in medium and small power lasers design.