Abstract: Illumination quality has important influence for the subjective visual feeling and work results in precise machining field.So it is valuable for illumination uniformity evaluation.A new approach for illumination uniformity evaluation based on the improved particle swarm optimization is proposed.The optimization fundamentals and implementation techniques are given，then its optimization goal and the fitness function of the optimization are described.An example is taken for verifying the feasibility and computation precision of the approach.Illumination uniformity function is simulated by the approach，and the result shows the probability of local convergence is declined and the precision is improved.